I have flowmaster 40 series delta flows in a charger. 440. 9.4 comp. Hooker headers. 2.5'' pipes. 230/238 @ 50 cam. They are obnoxious. Increase the size of any of the other factors, cam, compression, tailpipe, I think they would be unbearable. Some people dig the sound, and I do think they sound cool, but living with them is another matter. Heard a lot of good reviews about Dynomax Ultraflow mufflers and mufflers from
www.racemufflers.com or
www.racemuffler.com (can't remember). Don't believe that the "delta flow" stops resonance or in any way quiets a one chamber muffler. It sounds, resonates, and behaves like a glasspack. Even has that rattle/buzz when you rev up the engine quickly and then let off.