Modifying Please note that these modifications are carried out at your own risk!
They worked for me and I am merely reporting what was involved and what the benefits to me were.
I am not responsible for any problems that may arise from changing the standard specification of your car.

Modified Downpipe

This is a simple mod that can be applied to all the 4G63T equipped models and is a good basis for further modifications.

The example on the right of the picture was modified by Wayne Turley for his Lancer EX2000.   As you can see from the picture, the standard pipe (on the left) has a 90 degree elbow where the gases exit the turbo.  This creates turbulence and hinders the freeflow of gases.  Wayne replaced the top section with a bend cut from a lorry exhaust.  After refitting, turbo lag was reduced and throttle response was increased throughout the rev range.

Having since driven the car and experienced the improvements, I am surprised that Mitsubishi didn't fit a curved downpipe from the factory.

This is an ideal first mod and forms an excellent basis for further tuning. Combine this with an intercooler and an extra 3psi of boost makes for a cheap and reliable increase in performance.

 



The downpipe on the left is available from Top-End Performance in the US.
It's for the 2.6 Starion and is available to fit the standard Mitsubishi turbo or a Garrett.

Uprating the Clutch

This is a modification that became necessary after fitting a limited slip differential. The standard Mitsubishi clutch just wasn't up to the job. After a couple of hard launches it would start to slip and would then slip on the first to second gearchange for the rest of the day.

The clutch to use is one for a Sierra/Escort Cosworth. It doesn't matter whether it's for a RWD or 4WD model because the difference between them is the thrust bearing which is discarded.
Fitting involves re-drilling the flywheel and spacing the gearbox back from the engine. This is because the Cosworth clutch cover is about 6mm deeper than the standard Mitsubishi cover.

The flywheel has to be of sufficient diameter to be re-drilled for the bigger clutch. The flywheel shown to the right is from an early Starion and is insufficient. The face has to be nearly level with the ring gear teeth.

The modified flywheel shown is from a late model Starion. This has been re-faced and then doweled and drilled to the Cosworth clutch cover bolt pattern. This skimming has also reduced the thickness from 25mm to 24mm which helps reduce the amount that the gearbox needs to be spaced. (Please note that this is a useful side-effect. The flywheel is cast-iron and should NOT be skimmed any more than necessary.)

To increase the distance between the engine and the gearbox I have used two additional steel gaskets. These are 1.8mm thick each and so the total increase including the slimmer flywheel is 4.6mm.