On a NA engine, simple modifications like intake, exhaust, headers, ECU flashes will not provide sufficient power for you to note objectively (quarter mile, 60-130, trap speed.) It will likely alter your perception of the car (sounds better, deeper sound with exhaust, faster throttle with ECU flashes.) But it is doubtful that these simple changes will significantly change acceleration.I have a 997 gen 1. can anymore suggest an aftermarket air filter to replace the stock one and a silicon air intake also. does this mod make much difference to the hp. any help would be great.