Flowmaster 70 has good flow and is real quiet. Nobody likes them because most all flowmaster people want super loud
Cherry Bomb Turbo and Elite are pretty quiet too
I think either of the 3 would be good on a 454, the flowmaster 70 would be the best, and that's saying a lot, because I hate the loud flowmasters
Im running a Cherry Bomb Vortex on a 89 Camaro, with no cat, and its actually real mellow, only really hear it when you lay into it
Got a form of a glass pack (not quite as straight through as the original smittys) on my Dodge that is surprisingly no where near as loud as my old 454 with duals and true glass packs.