Then the 50 Delta Flow is for you. Don't get the regular, get Delta Flow. It makes the sound much deeper and more authoritive. The 40 was too loud for me on cruising, especially on my 04, about 70mph is the loudest range, 2000 RPM. THat's the point where interior noise is the loudest. Then you get to 4500RPM and that's where the engine sounds the meanest. If I get on it hard and make it rev to 4,500 RPM, I can be heard in my area of the neighborhood.