I'll tell you this, the Dynomax Super Turbos sound great when they are new (a little too quiet for me), but they are built with a fiberglass blanket that is wrapped around the center portion of the muffler & it will break-down pretty quickly & then the mufflers will get LOUD - VERY LOUD! Especially the 14" bodied ones, & the 3" x 16" versions. A good friend of mine has a 440-6 Challenger & bought a TTI headers-back system & went with the 3" Super Turbos - it sounded perfect when new. About 2 years later & not too many miles, the exhaust is SO loud inside the car it's not even fun to be in it for more than 15 minutes! My chambered mufflers & resonators combined would offer much better noise control than his current setup. So yes the Super Turbos do sound good, but they get loud over time. As far as the Walker Quiet Flows, they are 3-tube internals, there are no flow directors internally like Super Turbos have, plus the Quiet Flows have much smaller diameter flow tubes than the Super Turbos. A 2.5" Super Turbo will have 2.5" perf tubes internally (3 of them), while a 2.5" Quiet Flow will probably have 2" internal perf tubes plus CRF packing material - that's why they are quieter - they are a lot more restrictive.