Look, this is off of the Rod Millen site..
"RMM's New Celica GTS Stainless Steel Exhaust System is the best sounding exhaust we have ever heard on a car in this class. Not only does RMM's exhaust sound great, it increases horsepower too! Install RMM's Sport Intake
System with their Stainless Steel Exhaust System for an instant 15+ horsepower boost and a puuuurrrfect sound! RMM's Stainless Steel Exhaust Sytem is a perfect fit on the GT and GTS models.
If a body kit is installed, the exhaust can be easily modified so that it is flush with the rear valence of the kit."