I don't know the exact mufflers (they are big) that are on the 589ci wedge RR I crewed on but its a full 3" system to the bumper. Has 2.1/8" TTI step hdrs with 4" collector.

Engine dyno'd@694.2hp@5500, 693@5900, same carb dyno to track, car weighs 3800@line and has been a best of 130mph on a no headwind day.

Thats 679fwhp and shows a 10.34 with a 1.44 60, cars gone 10.30@1.421 60.best. Never been run on open hdrs. Perhaps the dyno was a bit stingy?