Okay...here's the deal...I am buying '99 SUS and would like to know if the performance parts (exhaust pieces mostly) for 2.5 GT models will fit. The engine is the same. The only difference is that the SUS has raises suspension, right?

Im taking your question to mean aftermarket parts for GT's and not stock parts right?

 

The Stock 2.5 GT's of that year did not have a special exhaust..it was mostly cosmetic differences that set the two models apart..engine and drivetrain remained the same.

Yes if you can find upgrades for the "GT" they will fit in yours. The only thing different is the suspension/wheels as far as I know.