I think the stock Yaris has enough power

[cali yaris]

I believe there is a way to eliminate the oversteer,

I *think* you mean understeer, not oversteer. It's difficult (but not impossible) to give a Yaris oversteer handling. Easier to make it neutral (my preference), and we all know (I think) it's designed to have understeer (= go straight when you want to be turning), which is safer for novice and untrained drivers.

increase oversteer/minimize understeer

stiffen the rear (springs, braces, sway bar, etc)
raise the rear tire pressure
soften the front
lower the front tire pressure
... and more...

[regal]

Originally Posted by cali yaris

I *think* you mean understeer, not oversteer. It's difficult (but not impossible) to give a Yaris oversteer handling. Easier to make it neutral (my preference), and we all know (I think) it's designed to have understeer (= go straight when you want to be turning), which is safer for novice and untrained drivers.

increase oversteer/minimize understeer

stiffen the rear (springs, braces, sway bar, etc)
raise the rear tire pressure
soften the front
lower the front tire pressure
... and more...

Your right I meant understeer, seems there should be some rear bracing that would help I tried all the above.

[echosqwat]

Originally Posted by regal

Your right I meant understeer, seems there should be some rear bracing that would help I tried all the above.

As one of the guys working on Echo performance back in 2001 here is what I did.

*Installed 26 mm Whiteline rear sway bar. Thats huge improvement.
*Instlled TRD rear stiffing kit. Cool factor but I'm not sure it did much to help with turning. Rear sway bar did that and rear tires really dont do much work on these cars. Think I would go front suspension bracing before rear.

*Intrax sport springs
*Koni Sport adjustable shocks
*Camber plate for front to allow camber adjustments.
*Front tower brace.

Rear bar really helps with understeer and also keeps front tires hooked up on exit of turns.

Next is to install lightest 15x7 wheels you can find with nice sticky tire like Falken RT615 or Bridgestone RE11, etc. Less rotating weight the faster you go in these cars. Probably would consider 14" whees as well. Just harder to find good tires.

I used Injen intake. Had cheap header and higher flow exhaust. It adds a little power but not much. I would say supercharger is best path with this motor.

The other big item for performance driving would be LSD. I could light up inside tire like crazy in turns. LSD would remedy that problem.

Lightweight flywheel is another good idea for the Yaris.

I'm looking to buy a Yaris in next several months so I'm putting together my must have mod list.

My Echo slaughtered Porsches at autocross events and I suspect a well setup Yaris would be very similar.