My opinion on this subject...
Dumps sound horrible. Every street Mustang without a built motor I have heard with dumps sounds aweful. I'm a fan of a smooth sound, whereas dumps are more of a vibration off the ground, and kills the tone mufflers have. Second off Flowmasters sound alright, but there are a lot better sounding mufflers out there. I prefer my Macs over the Flowmasters I used to have, and even plan to get rid of those this summer for something meaner. Third without a decent motor under the hood, the exhaust will never sound truly mean. It might get louder, but not what I would call better. Dumped race mufflers on a stock or near stock motor just wont sound like a good muffler on a race motor.
Obviousely when it comes to mufflers, we all do what we want, but when asking opinions, your going to get all kinds.