3" inlet / 3" outlet single chamber flowmasters under my 550hp 469 Poncho powered GTO
sounded like 55gal drums - DEEP!
tolerable sound level mid throttle cruising power but whack the go pedal and look out!
and not even a whiff of that fart can stench
had a base renta-cop hassle me a few times so I tried corking it up with standard 'turbo' style mufflers - couldn't keep gaskets
some months later got pulled over on base doing nothing, but this guy just wanted to check it out.. insisted I do a burnout in the parking lot - of course I obliged
most name brand high performance muffler companies have u-toob videos of their products in various output engines..
and of course cruise nights just about anywhere - stop and look what's under the ones you like the tunes from
btw, back then they didn't have the tube bending abilities they have now, mine dumped right in front of the axle..
in a truck you may have more options - good luck!
