I have a pair of LARGE turbo mufflers on my Jensen, then another pair of Dynomax bullets out back. It's not quiet but it sure sounds decent.

My motorhome has two 3" Flowmaster 50 series. In TANDEM. It's quiet at idle, sounds like a musclecar when pounded. Not loud at all.

I think mufflers in TANDEM is the way to quiet down an obnoxiously loud car....