I just got Pypes stainless shorty headers and Magnaflow clamp on Xpipe installed to go with the boom tubes racing axle backs. It actually got a little quieter with the headers and Xpipe, but really freed the engine up. It sounds very smooth and tame until you mash down on it. When I just had the axle backs on the car, it sounded mean as hell all the time. I think the Xpipe really balanced out the exhaust pulse from the V8 and it is flowing much much better. The Pypes headers do not make that much noise like I have heard on other cars with aftermarket headers(valvetrain noises). I can't wait to get intake and throttle body upgrades - just waiting on a decent programmer for the '010. I know it is very similar to the Bullitt tune, but I can't chance anything on a brand new car.