Personally, I think Flowmaster's and the like is just another case of paying way too much to get the name!!! I use plain old turbo mufflers my pal Roger sells at his exhaust/repair shop. Other then that, I'd just suggest reading Uncle Bob's post again..... Resonance is the big deal, just like in a stereo speaker enclosure... Other thing I do as a matter of personal preference is put the mufflers as far back in the exhaust system as possible.