So you're one of those broke DSMers who can't afford to spend any money on mods, huh? Well you're in luck - there are a few things you can do to get a little more out of your car. Some of these free mods will even prepare your car for future bolt-on modifications. Some of the following instructions involve removing emissions equipment, which in many areas is illegal and should only be done for off-road use (especially in CA). Performing some of these mods may prevent you from passing visual inspections as well as the "sniffer" test. Other mods outlined below focus on maintenance that you should do anyway. You'll need some basic tools and a shop manual to use as a reference. We'd like to thank kpt4321 (@kpt4321) for writing this content.

Step 1: Hack Aircan and Intake Area
The stock aircan has a rather restrictive opening, as well as a restrictive path for the air to take. It's best to remove the aircan so that the filter is exposed. The better way to do it would be to buy a new filter system, but this is for the cheap folks.

Step 2: Clean Throttle Body
Using a throttle body or carb cleaner, clean the throttle plate and the inside of the throttle body. IMPORTANT: make sure to stuff a rag into the holes at the bottom of the TB, or the cleaner will get in there and kill the mechanisms down there. Then, use the can and a rag to clean it all out. When you're done with that, you can start the car with the intake pipe unplugged, and spray a can right into the throttle body. You can also spray the can into any line that sees vacuum at idle.

Video of a non-DSM throttle body being cleaned:

You must be logged in to view this image or video.

Step 3: Verify that WOT is 100%
With the car turned off, have someone sit in the car and floor the gas pedal, and then check to see if you can rotate the throttle plate any more by hand. If you can, it could be due to the cable being out of adjustment (adjust on the back of the intake manifold, 2 bolts) or something like a floor mat keeping the pedal from going all the way down.

1. Loosen the two 10mm bolts that attach the cable to the intake manifold near the firewall.
2. Slide it back a little where you can feel little to now slack in the throttle cable near the throttle body.
3. Tighten them up to i believe its 3.5 lbs while holding the cable in place so it doesn't move.
4. Feel the slack of your gas pedal. it should be a lot tighter.
5. Don't go too far and tighten the cable where the throttle plate stays open all the time.

Step 4: Check IC outlet Pipe for Corrosion
The intercooler outlet pipe on the older cars has a tendency to corrode and leak out boost. Take the plastic fender liner off the car (take off passenger side wheel), take the intercooler out, and if it has ANY signs of corrosion, coat the entire upper pipe with JB weld. This is also a good time to:

Step 5: Open up the Fender Liner
You can use a sanding wheel (Dremel, die grinder, etc) to open up the vents in the plastic fender liner behind the intercooler in the wheel well. Some people just cut it out and replace it with a screen/wire mesh, that works too. ALSO, make sure that you have the duct in front of the intercooler in place and that it seals up. While the intercooler is still out:

Step 6: Clean the Intercooler
Use a cleaner such as simple green, greased lightning, or gasoline to clean out the inside of the intercooler. It gets filled up with oil over time, which can reduce it's efficiency. Make sure to get it nice and clean, until the water and cleaner comes out clear. Let it dry out completely.

A video on cleaning an intercooler:

You must be logged in to view this image or video.

Step 7: Remove the BCS Restrictor
If you do not have a manual boost controller, you can safely up the boost about 1-2 psi by removing the restrictor in the boost control solenoid.
(An Example)
(Another Example)

Step 8: Check Base Timing
Buy or borrow a timing light. Hook it up as per the instructions. Ground the black timing connector on the firewall behind the battery, and if you have a logger UNPLUG IT. Check to see that the base timing (crank pulley) is set at 5 degrees of advance. If not, loosen and rotate the cam angle sensor until it is. Note that the adjustment with the cam angle sensor mentioned here is for 2G vehicles using a 1G cam angle sensor (CAS). None of the 2G 4G63 vehicles were originally equipped with adjustable cam angle sensors.
(An Example)
(Another Example)

Step 9: Valve Cover Vent Breather
DO NOT DO THIS. Instead, read here: The 4G63T PCV System -19Eclipse90.

Replace the hose from the valve cover breather (left side of the valve cover) to the intake pipe with a simple breather filter and cap the intake pipe nipple. You can also use a catch can if you like. This keeps oil out of the intake pipes and the intercooler. If you want to do this even better, check out:
(An Example)

Step 10: Unplug Clutch Switch
Under the dash on the clutch pedal assembly, there is a switch that will only allow the car to be turned on if the clutch is pushed in. Just unplug this so that you can start the car without touching the clutch, it's better for the thrust bearing. The plug is on the front side of the clutch pedal assembly, so that it is only pressed when the clutch is all the way in.

Step 11: Pressure Test the Intake
This is one of the MOST CRUCIAL things you can do to make sure your car is runing properly! Does your car ever sputter, misfire, fuel cut, bog, idle badly, or smoke (black)under boost? It could be a boost leak! You need to build a pressure tester that will clamp onto the turbo and lt you use a bike pump or an air compressor to send pressure into the IC pipes and the manifold. ANY and ALL leaks should be fixed! The only thing I know of that should leak is the manual boost controller.
(An Example)

Ready to make real power? Check the Stage 1 Upgrade Path >

Step 1: Intake Pipe and Filter
A high-flow K&N filtercharger (or similar) intake filter will help throttle response and help all future mods achieve maximum performance. A hard intake pipe will also improve air flow over the factory rubber snorkel. This, along with the MAS modifications should take care of your intake needs at this stage. Read this article to learn how to install an intake in a DSM.



You can shop air intakes at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 2: Aftermarket Boost Gauge
The factory boost gauge is simply not accurate and shouldn't be trusted when raising boost levels. To avoid severe engine damage when increasing boost levels, an aftermarket unit is mandatory. You'll find many brands to choose from, all of which will do the job. Read up on how to install a boost gauge in a DSM.



You can shop for boost gauges at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 3: Blow Off Valve
The stock 2G BOV can't hold higher than stock boost levels. In order to avoid leaks when turning up the boost, it's necessary to replace the factory BOV with either a stock 1G BOV or an aftermarket unit. To avoid possible problems with idle, a BOV that recirculates back into the intake is recommended.

Here's a video to help show how to install a BOV:

You can shop for BOV's at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 4: Boost Controller
In order to raise boost levels, you'll need a boost controller. Whether it be a manual or electronic unit will depend on your budget. Electronic boost controllers are cool looking, but most have been known to be unreliable at over 25psi. At this stage, you won't be turning the boost up past 16psi, so it won't be a problem. But if you plan on moving up to the next stage, a manual boost controller may be better. Read the following article to learn how to install a manual boost controller in a DSM.


You can shop for boost controllers at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 5: Cat-back Exhaust System
A 2.5" or 3" high flow exhaust system is needed to gain more power. You can choose between aluminized steel or stainless steel depending on your budget. If your power goals are over 400hp, you'll want a full 3" system from the turbo all the way back. A "cat-back" system replaces the exhaust components from the catalytic convertor to the exhaust tip. A "turbo-back" system replaces the entire exhaust system, and is made up of a "cat-back" plus a downpipe and high-flow cat/straight pipe. For a tutorial on how to install an exhaust system on a DSM click here.



You can shop for exhaust systems at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 6: High Flow Cat/Straight Pipe
Replace the factory catalytic converter with a larger, higher flowing unit. For off road use, simply bolt up a straight pipe in it's place - of course, this is obviously not street legal. A 2.5 inch unit will be sufficient for a Stage 1 setup, but a 3 inch version will be needed if future plans include a Stage 2 setup.



You can shop for catalytic convertors and test pipes at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 7: High Flow Downpipe
The factory downpipe is very restrictive and should be replaced with a larger, better flowing unit. For Stage 1, a 2.5" downpipe will do. If future plans involve 400+ horsepower, consider a 3" downpipe. These are available in press-bent aluminized steel for those on a budget, or mandrel-bent stainless steel for those with a little more cash to spend.



You can shop for downpipes at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 8: Exhaust Manifold
The exhaust manifold can be ported, or can be replaced with a tubular style header that flows better. If you're planning on going with a full Garrett turbo, you'll need a manifold that is made to bolt up to a Garret turbo. It's common to have a break an exhaust manifold stud in the cylinder head. For a tutorial on how to remove broken studs, click here



You can shop for exhaust manifolds and studs at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 9: O2 Sensor Housing
In between the turbo and the downpipe is a 90 degree elbow called the O2 Sensor Housing. The O2 sensor screws into this housing. This is the last restriction in the exhaust system. The stock unit can be ported out, or you can simply buy a better flowing unit. If you choose to go with a "turbo-back" exhaust system, this housing will automatically be replaced. Read the following article on installing a 02 Sensor Housing.



You can shop for O2 housings at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 10: Fuel Pump, AFPR, and Re-wire
The stock fuel pump will not be able to supply the needed fuel for anything over 16psi of boost. Though you won't need to go past that in this stage, it's still cheap insurance to put in at least a 190Lph fuel pump to ensure you have enough fuel in case you want to raise the boost with race gas in the tank. It's also a good idea to re-wire the fuel pump for consistent fuel pressure. If you get a 255lph pump, you'll need an adjustable fuel pressure regulator so as to not overrun your factory fuel pressure regulator, which can cause a rich condition at idle. Here's a good article on how to install a DSM fuel pump.

Video tutorial for a DSM fuel pump install, part 1:

Part 2 of the install:

Fuel Pump Re-wire video:

AFPR Install video:

You can shop for fuel pumps at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 11: Intercooler Piping
The rubber intercooler piping should be replaced with better flowing solid pipes. Some replacements will come with a larger throttle body elbow (which is needed also). Please note that if a Stage 2 setup is in the plans, this upgrade may not be necessary as the intercooler piping will likely be routed differently with a front mount intercooler.



You can shop for intercooler piping at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Step 12: Turbo Upgrade
The smaller stock 2G turbo (the T25) is running at it's max. In order to gain more power, a larger turbo is necessary. You'll need a Big T28 or 16G turbo (with 2G install kit) in order to achieve the 300hp goal - either of these options will be great for autocross and/or road racing due to the fast spool. The Big T28 will look almost identical to stock on a 2g, which will be important for some people in emissions testing states.

Countless larger turbo options are available in varying configurations and some of them will require a special exhaust manifold, external wastegate and O2 sensor housing. This is the point where you'll have to decide what your car will be used for. The larger turbos are great for drag strip action, but not so great for road race and autocross use - something to keep in mind.



You can shop for turbochargers at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.


Drivetrain Upgrades

Performance Clutch
With more power on tap, the stock clutch probably won't last that long. It will start to slip, especially in the higher gears. This means it's time for a high performance clutch that can handle the increased horsepower. You can shop for clutches at ExtremePSI and our other supporting vendors, or even search eBay for deals on used ones.

Clutch install video:


Shifter Mods
If you have a 5-speed tranny, you'll notice that the shifting might be getting a little "loose". These transmissions tend to be notchy from the factory to begin with. The best solution short of a rebuild is to put in some good tranny fluid and replace the rubber bushings in the system with some metal bushings. This should help with grinding and missed shifts as well.

Shifter install video:


Limited Slip Differentials
If you have a front wheel drive DSM, you'll probably need an aftermarket LSD to keep the tires from spinning - especially if you plan on making more than the stage 1 power levels. FWD cars will have a more difficult time achieving fast 1/4 mile times compared to the AWD cars due to traction. Tranny rebuilds are the most opportune time to install LSDs, since the tranny is already being taken apart.




Auto Tranny Upgrades
Though you won't find as many turbocharged automatic transmission DSMs around as 5-speeds, there are modifications available to help improve shifting, help handle increased horsepower, and just make driving more enjoyable.





Is 300hp not enough? Check the Stage 2 Upgrade Path

2G Stage 2 Upgrades

Requires all of the Stage 1 Mods, minus the Upper Intercooler Pipe upgrade.


Step 1: Logging Software
Before you can safely begin making fuel adjustments, you'll need to know what's going on inside the engine. Logging software will give you this data and will help you decide what fuel delivery changes are needed, how much change is needed, and at what RPM point. Though datalogging is mainly for tuning, it's also a critical tool to prevent major engine damage as well.

» Shop for data logging options

Step 2: Warning Meters
Along with a datalogging solution, you'll want some gauges to help monitor the engine. While dataloggers allow you to analyze data after doing some test runs, guages are easier to read while driving. An EGT (exhaust gas temperature) gauge and probe will allow you to monitor the exhaust temperature exiting the engine. Extremely high temps generally translate into a lean condition and can be catastrophic. You can also go with a Wideband O2 system that will allow you to monitor the air/fuel ration of your car while driving. This will tell you exactly how rich or how lean the car is running, allowing you to adjust the fuel curve accordingly.
» Shop for Gauges

Step 3: Fuel Controller/Engine Management
In order to control the flow of fuel of the larger injectors, you'll need some form of a fuel management system. The factory system simply cannot control the changes you've made/are going to make. There are a variety of ways you can go here. The most common route is a piggy-back style computer which still uses the factory MAS in combination with a reprogrammed EPROM chip that plugs into the factory ECU. The drawback to this is that some cars didn't come with an ECU that utilizes an EPROM, making an ECU swap necessary. Another option is a stand alone fuel system which completely replaces the MAS system altogether. Stand alone systems give you much greater tuning capability, but may require more knowledge of fuel tuning than the average weekend warrior may possess. Either route you choose will allow you to run larger-than-stock fuel injectors - which will be needed very soon.


» Shop for Fuel Controllers
» Shop for ECU Upgrades and Stand-alones

Step 4: Fuel Injector Upgrade
To supply the amount of fuel needed for a larger turbo, the stock fuel injectors will need to be replaced with higher flowing units. The larger the turbo you plan on upgrading to, the larger the injectors you'll likely need. If swapping in a 16G turbo, you can get away with 550cc injectors. Most T3/T4 combos will require at least 650cc and up.

» Shop for High flow Fuel Injectors

Step 5: Front Mount Intercooler Kit
The stock side mount intercooler will not be able to cool the amount of air flow needed to produce 400hp or more. Thus, it will need to be swapped out for a Front Mount Intercooler. Some kits require some trimming of the steel bumper and some dremeling of the plastic bumper cover. Most "street" kits will do for this stage. But if more than 400hp is desired, you might want to consider a "race" kit which will have a larger core for better cooling characteristics.

» Shop for Intercooler kits

Drivetrain Upgrades
Performance Clutch
With more power on tap, the stock clutch probably won't last that long. It will start to slip, especially in the higher gears. This means it's time for a high performance clutch that can handle the increased horsepower.

» Shop for Aftermarket Clutches

Lightened Flywheel
To help your engine rev quicker, try a lightened flywheel. Most are stronger than stock, and can handle the abuse seen at the track.

» Shop for Flywheels

Shifter Mods
If you have a 5-speed tranny, you'll notice that the shifting is likely less-than-desirable on the 90-94 cars. These transmissions tend to be notchy from the factory to begin with. The best solution short of a rebuild is to put in some good tranny fluid and replace the rubber bushings in the system with some metal bushings. This should help with grinding and missed shifts as well.


» Shop for Short Shifters
» Shop for Tranny Fluid

Limited Slip Differentials
If you have a front wheel drive DSM, you'll probably need an aftermarket LSD to keep the tires from spinning - especially if you plan on making more than the stage 1 power levels. FWD cars will have a more difficult time achieving fast 1/4 mile times compared to the AWD cars due to traction. Tranny rebuilds are the most opportune time to install LSDs, since the tranny is already being taken apart.

» Shop for Limited Slip Differentials

Auto Tranny Upgrades
Though you won't find as many turbocharged automatic transmission DSMs around as 5-speeds, there are modifications available to help improve shifting, help handle increased horsepower, and just make driving more enjoyable.

» Shop for A/T Upgrades



Other Upgrades/Modifications

You must be logged in to view this image or video.

Helmet
If you're planning to be putting down a ton of power, it's a good idea to start thinking about safety - both yours and those around you. First of all, you should be taking your car to the track regularly to do all of your testing. Keep the racing off the city streets. When you're at the track, you'll notice they have some rules and regulations in place for safety. Most tracks require you to wear a helmet if your car runs a 13.99 second 1/4 mile time or faster. If you're doing any road course or autocross racing, a helmet is always required.

You must be logged in to view this image or video.

Roll Cage
Most tracks require your car to have a roll cage installed if your car runs an 11.99 second 1/4 mile time or faster. If you're doing any road course or autocross racing, a roll cage is totally necessary.

You must be logged in to view this image or video.

Racing Seats/Harnesses
For more safety and driving control, look into some good supportive racing seats and harnesses to keep you firmly planted in the proper driving position. You'll find a variety of manufacturers for the racing seats, including Sparco, Corbeau, Recaro, etc. Sparco Racing seats tend to be quite popular among DSMers for some reason.

Once you've completed these mods, and only then, will you have enough knowledge of how these cars handle power to go further. You should now know how tricky the art of tuning can be, and you're likely well versed in spending money on parts and repairs. It is possible to get over 600 horsepower out of the 4G63 engine, but it will require rebuilding the motor with some forged pistons, strong rods, more aggressive cams, porting the cylinder head, etc. You can even go with a stroker kit to add displacement for bigger torque! Be prepared to spend some big money - especially when things start breaking due to the excessive power output. And things will break.