It's what you can do with what you have . As 10 sec Dodge say's . The Challenger is a heavy car. It runs good and handles good on the street with the 5.7 . And the SRT 8 is even better . From what have been told . I haven't driven one. Power steering and all sort of stuff rob power from the engine . Under drive pulley's can help some . Or take the power steering off as I did on my 71 Buick GS 455 Stage 1 and put a manual box on . And the air conditioning . I don't plan to do that and dont think many other's would . But it does add HP back to the car. I priced the Magna Flow exhaust for my 6 spd yesterday . The best pipes and everything . Was $1500.00 at my friends muffler shop. 10 sec. Dodge is that what you have on your's . And what brand header ? I can handle a little more rumble after getting used to the stock exhaust . I think 10 sec. Dodge has shown what the Challenger can do with minor mod's. Good Job.