The first set of modifications you should make are originally credited to Dempsey Bowling and his "Recipe A." Of all the mods you can make, these are probably the safest, and the most effective. If you are going to make any mods, these are the ones to make. If you're not going to do them all at once, then at least do them in this order for the best results. For these mods, you shouldn't need additional guages. The set is broken down into three parts:
Install a high flow exhaust system. You have an infinate number of options here, but keep a few things in mind. Contrary to the general believe that opening the exhaust will effect low-end torque on a turbo engine, opening the exhaust on these engine has no negative effects on most setups (see below). It does have a profound effect on the high end where the stock exhaust reaches it's limits and the engine seems to "run out of breath." So basically, go as big as you can make fit. The least expensive method is to have a muffler shop cut off the exhaust pipe at the catalytic converter outlet. Then have a them install 2-1/2 inch exaust pipe all the way out without a muffler. By using smooth bent pipe (known as mandrel bent), you will have an exhaust that is more than large enough since the downpipe from the turbo to the cat is already 2.5 inches. This is frequently called the "cat-back" mod. The turbo cuts most of the exhaust noise, so not having a muffler is not a big deal. If you don't like the additional burble of the larger exhaust, install a high-flow muffler such as a Dynomax or Borla. For more information on exhaust upgrades, see the Upgrading The Exhaust page.
The only exception is on engines with very small turbochargers (the stock Mitsubishi turbo on 1988 and up Turbo I engines) and VNT engines. With these, going larger than a 2-1/4" mandrel bent system will likely result in "boost creep", where the boost rises past the correct amount as engine RPMs increase, eventually hitting overboost shutdown. Going to the larger Garrett T04 unit (see Turbo Performance page) well address these problems.
Install a Performance Engine Control Unit (ECU). This can either be a Mopar Performance ECU, which is available at your Mopar parts counter through the Mopar Performance Catalog, or a custom calibration from FWD Performance or Relentless Racing.
The Mopar Performance ECU removes the peak boost timer described on the Engine Information page and gives you peak boost all of the time. It also may have more aggresive timing, spark, and fuel delivery curves, depending on the model. Overboost shutdown will still occur at around 14 psi. One thing to note is that some Mopar Performance ECU (depending on the model year) do not have a cruise control function. So if you have cruise now, you may not have it after you install the new ECU. The Mopar Performance Calatog is not clear as to which ECUs have this shortcoming. Also, some of the ECUs don't use the oxygen sensor during idle (some of the Stage II units) and some don't use it at all (the Super 60 unit). There are no ECUs available for Turbo III or Turbo IV units and there is also no warrenty on any of them.
The FWD Performance and Relentless Racing "Stage I" computers give you all of the benefits of the MP unit, but use the oxygen sensor for proper emissions. Also, these units usually have higher boost settings and are available for Turbo III and Turbo IV engines. They also have more aggressive calibrations in Stage II varieties and beyond.
Install a K&N filtercharger. This can be a drop-in replacement element, or a cone filter, which requires you to come up with a way to mount it and run it into your intake. If you choose this as your first mod (as I did) you may see some strange effects. I simply installed a K&N drop-in and I found that my throttle response had changed. For one thing, it seemed to make the turbo spool up faster, while at the same time it made my throttle body seem like it was too large. Whether I was at 1/2 throttle or wide open throttle (WOT), I got almost the same amount of power out of the engine. It made shifting somewhat jerky and made take-offs a little tricky in slippery conditions. The reason for this is that my intake was flowing so much better than my exhaust that 1/2 throttle was enough to reach the flow capacity of the exhaust. I found that 2/3 throttle gave me more power than WOT, at times. So the K&N, by itself, does little more than decrease turbo spool-up times (which is nice) and maybe increase gas mileage slightly. However, to really take advantage of the K&N, you'll need to open up your exhaust system as described below. There is the added benefit that the K&N elements actually filter better and last much longer than a paper element, which is always a good thing. I added an additional piece of window screen inside the airbox, in front of the filter because the grooves of my K&N kept getting clogged with bugs (so did my paper filters). To see a real performance increase, you'll need a performance computer or to increase the boost. For more information on intake upgrades, see the Upgrading The Intake page.
So by installing this set of modifications, you will have made the first and often the largest increase in performance on these engines. It is the safest set of mods available because the computer still has control over the engine and turbo. Also, you have set yourself up with a good foundation for future mods, since they will perform better with these mods done already. The total cost for these mods should not exceed about $300 - $400, which is quite cheap if you look at what it costs to upgrade most other cars with performance parts these days. Starting in 1999, Mopar started phasing out its 2.2L performance parts, but the Mopar Performance ECUs still seem to be available.
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Updated 04/05/2004.
Copyright © 1996-2004 Russ W. Knize.