I agree with Patrick....have a 5.0HO engine with similar OD (a bit lower final drive ratio, though, at 3.7) and fairly small primary pipes leading into a 3" muffler. My cruising range is from 2,000 to 2,500 RPM and until I want to pass someone you wouldn't know it was next to you from the volume.
On the other hand, if I do a burnout you can hear the pipes for blocks....I don't do that much, though!
Cheers!
Dugly
