Proton Satra GTi with 4G93 1.8 DOHC 16v engine.

Dummies Guide to Vehicle Modifications!

The Proton Satria GTi 1.8 model was a fantastic package to be provided to the world market. With the Mitsubishi 4G93 DOHC 16v engine, producing 103kw of power, it revved hard and handled well with a very well designed factory suspension setup. With disc brakes all round, a solid 5 speed manual transmission, it was the first real Mitsubishi / Proton hot sports hatch out there with good looks. Like any factory set-up, the vehicle responded very well to upgrades especially in the exhaust department.

From 1999 to 2002 the vehicles utilised the full Mitsubishi running gear and electronics, making these very popular for turbocharger conversions utilising ex Mitsubishi CC Lancer GSR Turbo and ECU packages. From 2003 on Proton moved to a more cumbersome Siemens ECU / Map sensor set-up which did not have the same level of support in terms of after market. Most people commented that the newer model had less power and was less responsive.

This section is to be used as a guide in your modification – we will be breaking this into sections to provide a well balanced vehicle. Additionally the modification package will be set-up so that as you increase the power of the vehicle, your alternative items like brakes etc are matched to your new power level. This guide has also been done in an order which provides successive gains from the modifications power wise. Jumping say to number 20 first, may result in a LOSS of power until you have done other items to match its effect.

RPW does not take any responsibility for people performing these modifications on there car without professional involvement. Check with your local government regulations before modifying your car as these items may not be legal in your country.

Group 1 Modifications

The group 1 modifications are designed for the every day driver, wanting improvements across the board without sacrificing road comfort, fuel economy or drive ability.

These are also the baseline modifications for the more extensive Group 2 modifications.  Standard horsepower for the vehicle is 65kw on average at the flywheel.

1. Quick Shifters

The Mitsubishi/Proton gear shifter system is one of the more average ones on the market. Unfortunately, Proton have continued to use the older Mitsubishi metal base design, which is honestly quite terrible in standard form. Very sloppy and prone to wearing hard on the bushes. This is one of those modifications that can be done at any time. Our Modified units suit most people who want something to reduce the long throw and give a more precise feel to where the gears are located.

For those performing any level of competition work, or just want something a little more extreme, this unit reduces overall movement by as much as 50% over stock and provides a much better feeling of control over where your gears are and enabling faster gear changes. For those wanting to go more extreme, RPW also manufactures replacement bushes for the shifter to further reduce the movement of the metal base where affixed to the vehicle.

2. Air Filters & Cold Air Induction Kits

The factory air box system on these vehicles, is quite restrictive. There are several ways to free them up – we recommend several options

  1. Fitment of a K&N Factory Replacement Air Filter for those wanting the Stock look, with improved air flow and throttle response.
  2. The 1999 – 2002 vehicles utilises a MAF – Mass Air Flow Unit which measures air volume and records back to the ECU as the primary referencing source for all ECU management. Fitment of the incorrect universal air filters creates many idling, running rich and other issues with drive ability. RPW recommends utilising the K&N Specific K&N Ram-pod filter that is oval shaped with an oval shaped adapter. This way we ensure that you do not have any ECU tuning issues.
  3. The 2003 vehicles utilise a MAP sensor, which can utilise any universal design air filter. Highly recommended upgrade over the stock air box design. No tuning issues result from this.
  4. Fitment of a Cold Air Induction Kit. At this time there is only a kit available for the 2003 model vehicles utilising a pre manufactured plastic pipe kit which relocates the K&N Ram-pod filter into the front guard.

The Cold air kit relocates to the front bumper, pulling cold air especially where utilised with a aftermarket front bumper. Of course a K&N large pod filter is used, RPW recommends purchasing one of our K&N Pre Filter Charger Kits that provides additional filtration and resistance to water

This should produce an approximate gain of around 1 – 2kw with improved throttle response and torque.

3. Fuel Pressure Upgrades

The 1999 – 2002 model vehicles, will eventually need one of these units. Now is a good time to do it as it will definitely help with future modifications. For the 2003 + model vehicles, this is an absolutely necessity. This is the one thing we believe that these vehicles should always have fitted regardless of how little, or much you modify the vehicle.

Quite simply the factory vehicle has been tuned for maximum Economy. This has resulted in a flat spot off idle when accelerating hard from a standing start of from a cruise mode situation. The reason for this is Proton have tuned very lean on the accelerator pump settings, resulting in the lack luster performance on throttle, but excellent fuel economy. This is especially noticeable on the 2003 models with there MAP sensor setup.

  1. Fitment of the Fuel Pressure Regulator kit eliminates this flat spot, whilst only marginally reducing your fuel economy. Without going into huge detail, trust us when we say, flat spots are eliminated, your car will actually accelerate properly without hesitating and your fear of being run over at stop signs will diminish rapidly. This is an easy bolt on kit and can usually be done in around 1 hour maximum.
  2. A new CNC Manufactured bored out fuel rail, which increases the fuel capacity within the fuel rail. This enables upon acceleration, a greater volume of fuel to become available before leaning out. This also reduces the tendency to pulse the fuel and create disturbances in the fuel flow, providing a smoother transition to power. This is a new RPW product. This is a recommended upgrade for those looking to go multiple throttle bodies / forced induction later.

This will not produce any HP Gain, but will provide an approx 10ft/pd torque improvement at low rpm off idle.

4. Exhaust System Upgrade

Okay you have done the easy mods, now time to do something about the exhaust. Contrary to what many people believe, without any form of induction work or fuel work, fitment of exhaust upgrades are only marginally beneficial. The stock system on these vehicles is usually an Asthmatic 1 5/8″ system with some sharp bends to a restrictive rear muffler. At this point you must reach your first major decision on where you wish to go with the vehicle – in summary we recommend the following options

  1. Naturally Aspirated – Stock Computer – You are only after mild improvements to make the car sportier, but don’t intend to do any real serious mods. This being the case stick with replacement of the stock exhaust with either a rear muffler upgrade only 2″ Lukey Ultra flow oval shaped unit, or complete it with a 2″ press bent exhaust system with new muffler and resonator. Cat converter should remain stock. Any larger on the system would not provide without sufficient more expensive mods, any real gains.
  2. Naturally Aspirated – Piggy Back ECU – you are after mild to medium improvements to make the car sportier, with slightly more than average vehicle modifications. This being the case, a 2 1/4″ diameter replacement exhaust with a new lukey resonator and muffler. No need to go mandrel bent unless you have money to throw away. This setup will handle the majority of modifications we have listed short of turbo systems
  3. Naturally Aspirated – Haltech EMS – okay you are an extreme modder. Twin throttle bodies, camshafts the list goes on. In this case either a 2 1/4″ mandrel bent system or a 2 1/2″ press bent system, again with lukey units. Only real difference is addition of a 2 1/4″ or 2 1/2″ cat converter depending upon how extreme you are going
  4. Turbo Charged – no more need be said. But don’t go throwing your money away on a 3″ mandrel bent system. A 2 1/2″ press bent system, cat converter with Lukey units are more than you will ever need if you are retaining stock internals. Go Mandrel bent if you plan on forged internals with boost levels above 17 psi. Keeps the car quiet, no droning and has a great sound.

RPW Systems done in house, are guaranteed to not drone, have a great sound and provide much improved throttle response and in some cases, improved fuel economy.

These can produce small gains with the basic systems of around 2 – 5kw at the wheels, with increased rev ability and torque.

5. Suspension Upgrade – Level 1

Suspension Package? Level 1? What is this. Basically at this point you are still have a mildly modified vehicle and want to just improve the looks slightly and handling. We recommend in this situation the following

  1. Replacement of stock springs with some lowering units – either 30mm or 50mm lowered units depending upon how low you want to go.
  2. Fitment of a White Line strut brace. Reduces the tendency of the vehicle to float on the road and makes it less sensitive to changes in road camber, resulting in less need to constantly adjust the steering wheel to keep the car driving straight. We recommend fitting one to both the front and rear of the vehicle. Fitment of rear unit will require some cutting of plastic covers.
  3. Fitment of upgraded sway bars are also found to be very positive. Reduction of sway around corners, especially with several people in the car work well.

This package will proved a well balanced vehicle, capable of handling corners at higher speeds, will feel safer at higher speeds especially above 100km/hr. The steering will feel more precise and you will have overall more confidence in pushing the vehicle harder.

Group 2 Modifications

Okay the basics are done and you have a plan. The following mods require you to decide, which of the following ways you are going which will be

  1. Staying Naturally Aspirated and going a little more extreme
  2. Looking to turbocharge the vehicle.

1. Extractor Upgrade

Not all extractors are equal. But in reality, any half decent designed unit will be an improvement over the stock manifold on the vehicle, although to date RPW is the only firm that manufactures a true 4-1 Extractor kit for the 1.8 DOHC cylinder heads.

Our 4-1 race design kits bolt up to the factory cat converters without any modifications. Increased throttle response, torque and horsepower all result from this. RPW was the first to design a superior system for these cars, and our systems are found on more modified vehicles for the Satria GTi models. Many of our systems end up in Malaysia (Home of Proton) in the endurance races due to the superior torque and flow designs of our 4-1 Race Design Systems.

If your plan is to go turbo, then save your money and jump ahead several more levels. This is not for you. For everyone else, this will complete the balance of your exhaust system modifications.

This package adds around 5kw at the flywheel with increased torque and improved upper acceleration and rpm range.

3. Single Throttle Body Upgrade / Thermo Block Kit

Time to look at improving throttle response again. Now if you are wanting to go a little more extreme, to a twin system then you need to wait a little longer. For everyone else, time to start looking at improving throttle response, even if you are going turbo.

The stock throttle body on the 4G93 DOHC engine is 58mm. RPW Recommends for the majority of owners to do the following

  1. For all owners, upgrading the stock to our bored out 60mm is very beneficial. Improved throttle response and mid range torque.
  2. The next alternative is to look to fit a Modified 63mm unit. Improved low rpm gains and top end performance especially where utilised with a better intake manifold and camshafts.
  3. RPW has billet 70mm units which to be used with our performer series inlet manifold for those going with much higher mods in the future.

Whilst this work is being done, we recommend fitting at the same time a Thermo Block Kit. Consider this an extension of the cold air induction kit be reducing heat soak into the intake manifold from the engine and the throttle body which have hot water running through them. This drops the average intake temperatures by 25% overall resulting in improved combustion, fuel economy and throttle response.

This package adds 2- 4kw at the flywheel, but does improve throttle response and low rpm drive ability. The thermoblock kit reduces heat soak and this allows the engine to maintain maximum ignition timing with max throttle response.

4. Brake Upgrades – to suit all future modifications

Before doing any further power or suspension modifications, brakes now need to be seriously looked at. The stock brakes on the front of the Satria is a 256mm single piston caliper package with a 260mm rear disc brake. This is a very good design for the majority of average drivers, but like anything, it will not handle consistent spirited driving.

  1. For those wanting something marginally better, and are not planning on doing ANY MORE Horsepower mods, then minor upgrading of front brakes only. Retaining stock calipers, fitment of some EBC Green Stuff brake pads and slotted Rotors is very beneficial. Improved braking by around 25% with better feel and dramatically less brake fade.
  2. For those wanting the final level of brakes, fitment of a 276mm Twin Piston front brake package and brake master cylinder upgrade is the final step. Guaranteed no brake fade and this large rotor will fit very nicely inside of any 15″ or larger rim this is highly recommended for any turbocharger conversions or competition use.

5. Suspension Modifications – Level 2

Okay ready to take the final plunge for power and hit that turbocharger or twin throttle body with computer. Wrong. Lets take a look at your suspension again. Factory shock absorbers will increase your braking distance, especially if they have been running inside lowered springs for 10 – 20,000km. They are marginal at best when new. Time to go for more extreme options

Shock Absorber Options – three choices here with standard type strut assemblies

  1. Fitment of KYB Excel-G replacement units for the more budget conscious. Retains improved handling over stock.
  2. Fitment of KYB AGX units. These are externally adjustable and are perfect for the all round street / strip / circuit car. You can set them soft when your on the road, hard when your driving hard. Adjustment takes less than 1 minute
  3. Fitment if Koni Sports Inserts. These are similar to the KYB AGX units, but are serviceable and provide that little bit more control. They are a more precise unit, externally adjustable on the front only, internally adjustable on the rear. For the more sports conscious person these could be the better choice.

Coil over Strut Assemblies

  1. We recommend the Tien units specifically manufactured for Australian Conditions. To put it quite simply, many Japanese units are set very very hard, so even on there softest unit the car is very harsh, hurts kidney’s and actually has worse handling as it skips all over the road. The hardest setting on the Tien units, are equal to the softest setting on the Japanese normal imported units. We cannot recommend these enough – they are simply fantastic with the ability to set your road height, rebound levels etc.
  2. These Tien Units are also available to be electronically adjusted on there rebound rates via up to one independent controller per corner, or one controller on all four units as an example. Mostly for extreme racing only.
  3. K Sport is our second choice of Coil Over kits. These provide the best balance of road sport and comfort. We use them on all vehicles where possible and have found them to be excellent for duel use applications.

The final items we to improve your suspension is as follows

  1. Fitment of a RPW Upgraded front engine mount. This polyurethane improved unit, reduces axle tramp and engine movement. Increases traction and reduces the vehicle ability to get that dreaded engine bounce especially on wet roads. Any serious drag racer would feel the benefits of one of these straight away.
  2. Fitment of a Whiteline Anti Lift kit to the front lower control arms. In essence, this increases the caster of the front lower control arms and lowers there center of balance, to provide a reduced tendency to “Lift” the front of the car upon accelerating. Requires a wheel alignment straight away.

RPW Does not recommend replacing the balance of the vehicle rubber mounts with Polyurethane ones for any street going vehicle unless being used for competition use. This results in a very very harsh vehicle on the road with much increased road noise and vibration. We feel the packages we have recommended provide that best balance of street vehicle and performance without sacrificing drive-ability.

6. Drive Line Upgrades

There are three main drive line upgrades which can be done, which go a long way towards improving the reliability of the engine as well as drive-ability.

  1. Billet Lightweight Front Under Drive Pulley – this unit reduces both the moving mass of the front harmonic balancer, as well as being physically smaller by around 25% diameter over the stock unit. Helps to make the car rev faster, spins up faster and higher. The reduction in drive ratio’s means that the power steering and alternator are turning less at higher speeds further reducing engine load. This is just small enough to reduce load without reducing the effectiveness of the operation of the alternator and power steering units.
  2. Clutch Kit – At some point your clutch will need upgrading. Two options available – for naturally aspirated drivers a standard cover plate with a semi ceramic five pucker clutch disc package. This will increase clutch efficiency by 50% without any extra pedal effort required. For turbocharged vehicles, this is upgraded to a Heavy Duty unit with the cover plate strengthened by an additional 25%. This provides slightly increased pedal effort and more tendency to be shuddery on take offs but will handle the higher torque characteristics of a turbo.
  3. Lightweight Billet Flywheel – this has two benefits being increased strength over stock units and also make the semi ceramic clutch units more drive-able by not allowing them to shudder as much. Second benefit is that they are lighter and enable the engine to rev easier, faster with less reciprocating weight. No loss of torque but more willingness to rev quicker and harder.

Group 3 Modifications

Now we are down to the serious modifiers. You are usually plan on going turbo or serious Naturally Aspirated Throttle body packages. Comfort and drive-ability is usually second to engine performance and speed is your goal. These next levels are also the most expensive ones, but be warned, if you have not done any of the Group 1 or 2 Modifications yet, you are WASTING YOUR TIME AND MONEY. Finish them first.

1. Computer Modifications

Okay two choices. EMS or Piggy Back. Pro’s and Con’s. Note to date – the 2003 models are only compatible with a full aftermarket EMS System, no piggy back ECU systems are compatible with the Siemens ECU at this time. But We like to think of it this way.

  1. If you are still budget conscious (And your at Group 3?), then stick with the piggy back. This is only applicable for staying with single throttle body / naturally aspirated systems, small camshafts .
  2. For all other forms of modifications a full replacement EMS is the way to go. Much more advanced tuning, with options like shift lights, in built boost controllers, many many more mapping points, much finer tuning or doing cam work etc this is the ONLY choice. The stock ECU system is unable to cope with large camshafts and is definitly not turbocharger compatible.

Haltech Interceptor / Greddy Emanage systems – provide a great unit for baseline tuning. We recommend for people who have gone all the through the Group 1 & 2 level modifications, but don’t plan on going any further. Neither of these systems though are compatible with either a twin or forced induction setup due to either the MAF unit or the siemens factory ECU. This is strictly naturally aspirated, single throttle body packages only.

Haltech EMS systems are what RPW specialises in. We make our own plug and play ECU packages which means we can have your car running in around 15 minutes with a Haltech EMS system on there. With the inbuilt boost controllers, and hosts of other functions, these are way ahead of trying do piece together a piggy back with separate boost controllers, shift lights, gauges etc.

Note that RPW does not recommend plug in pre programmed computer chips. These are not tuned in real time on a dyno to suit your individual car. As you modify your vehicle you move further away from the standard average formula of your engine output. This requires significant tuning and can only be done in real time, not on a computer 3000miles away from your car.

The interceptor units usually provide around a 5kw gain at the flywheel, with improved drive-ability and torque. The full EMS units provide a little more at this point, but really show there benefit later with more extensive modifications.

2. Intake Manifold Upgrade / Twin Throttle Body Conversion

If you are remaining Naturally Aspirated you have several options.

  1. First you can go for a single throttle body RPW Performer Intake Manifold with Internal Ram Tubes. Massive throttle response, Haltech piggy back system great looks without extreme levels of tuning required. Significant torque improvements and can be utilised up to a single 65mm throttle body
  2. Upgrade utilising stock manifold, modified with fitment of a second throttle body – twin throttle body conversion. Either twin 50mm, twin 55mm throttle bodies work very nicely for a progressive throttle response and great top end rush of power. This system is fantastic and highly recommended if insurance premiums are a worry. Requires a Greddy Emanage to run this effectively.
  3. The third option is a combination of a RPW Performer Intake Manifold and twin throttle body. Massive plenum chamber, improved air flow, progressive throttle response, this is nearly equivalent to a quad throttle body kit without the side effects and all of the benefits. Massive air flow and the ability to tune with EMS system. Not turbo compatible of course.

The twin / single manifold upgrades in n/a form can take the car with tuning up as high as around 110 – 115 kw at the flywheel. Twin units produce much stronger mid range acceleration, single units much broader torque from a lower rpm range.

3. Turbocharger Conversion Package

What more can we say other than your a horsepower and boost Junkie. Welcome to the rest of the world. This combines extreme levels of torque and power, with neck snapping acceleration. It comes at a cost though, increased fuel economy, higher insurance and lots of money. But lets get something clear first. As stated earlier the Mitsubishi Lancer GSR Turbo model Turbocharger assembly will fit straight onto the Proton Satria GTi model engine. With the baby TD04 turbo, 180kw with proper ECU management is very easy to obtain and fairly cheap to do – as long as it is done properly. For those wanting more, a full custom turbo package is available utilising Garret ball bearing turbo’s etc.

  1. Anyone believing they can effectively fit a turbo kit on there car safely, properly and legally for under $5000.00 AUD$ is just plain dreaming.
  2. These engines in stock form will not handle above 1 PSI boost without aftermarket computer management despite what people believe. 25 : 1 rising rate fuel pressure regulators, larger injectors, moving the distributor to retard timing all these tricks – none work. Don’t skimp.
  3. 5th Injector systems are something that came and died in the 80’s. Quite simply this does not distribute fuel properly to all cylinders, and still does not provide ignition timing adjustment

Do the job properly and although it may cost more, it will last longer, provide trouble free maintenance and be everything you want it to be.

  1. For boost levels up to 7 psi can be done safely on the stock head gasket dependent upon tuning and inter-cooler efficiency.
  2. For boost levels up to 14 psi requires an upgraded decompression head gasket which RPW manufactures.
  3. Do not boost above 14 psi on the stock piston / conrod setup otherwise you will learn what a banana conrod looks like.

The 4G93 DOHC engine at around 13 psi is good for around 200kw at the flywheel at the extreme. With forged components you can go up to as high as 250kw reasonably at around 20 psi boost.

Our final advice – if 200kw is not enough for you – the finish reading this page, and instead either look for another car or look to do a engine swap to a larger Mitsubishi engine.

Average price of a turbo kit fitted, installed with a FMIC and Haltech ECU System is around $8500 – $9000.00

Did you like our guide? Something did not make sense. Please let us know and we will try to update this with more relevant information etc. We hope this helps you plan your vehicle modifications in a more informed manner.