the original owner put the evolution motorsports (evoms.com) stage 3+ kit on the car. The numbers that evoms claims is similar to the X51 kit and according to the salesman that I bought it from (who is driving a 05 997C2S) the car is a little quicker. The stage 3+ kit is Headers, Exhaust, Intake, and Chip. It sounds much more aggressive then the stock set up.

I also have the short shift and it is great.