I have heard both and decided on the MAC. The Flowpaths have a meaner rumble and don't sound as hollow as the Flowmasters. The only thing I don't like about MAC stuff is the coating. It doesn't hold up. But lets face it... it's exhaust components so no real biggie. Plus, MAC's Pro Chamber crossover is the best flowing crossover you can get for the money. If I didn't get the MAC crossover I would have gone with the Dr. Gas X-pipe.
I'd highly suggest installing a set of long tubes along with everything else. If you don't and you want to go with long tubes later you'll have to buy another crossover. People say that adding long tubes will hurt low end torque on a stock engine. I installed them on mine when it was completely stock and it made a huge difference in power all the way accross the RPM range.
Here is a sound clip of my car with a full MAC exhaust system consisting of long tubes, Pro Chamber, and cat-bac.
http://www.mustangwarehouse.com/sounds/sample002.wav
Take into consideration that this was recorded when my car was completely stock. It sounds even meaner now with the heads, cam, intake, and all the other mods.
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Too much to list. Best ET on the car so far with stock 2.73 gears - 13.73@102mph
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