Between the 2,MAC & Dynomax,go for the Mac.
I had Dynomax super turbos on my car for a year and wasn't impressed at all. They don't have the performance sound that a muscle car should have,plus,look at how the exhaust flows while trying to exit once,I couldn't believe I even installed them *LOL* Now i'm running 2 chamber Flowmasters,but have thought about changing to MAC.
Goto
www.mustangworld.com they have a section with a bunch of audio files of different exhaust set-ups.
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Paxton Blown 87GT
ICQ#112698436