Just my 2cents worth:

On the 340 Demon I have a 2.5" H-pipe TTI system and even thought it is awsome, I need to change the mufflers for a drowning noise while at low rpm (2k rpm specifically) in 4th gear. It's not the systems fault I probably need more gearing I run a 3.23 rear gear now. Good ground clearance and neat clean bends. After 5 years it still look awsome. Also I am running factory exhaust manifolds. Very helpful when deciding on what part to use.

On the /6 66 Barracuda automatic I went Accurate and went with the upgraded diameter. Not only does it look awsome but nobody knows is not factory. Quiet and clean.

Both systems are awsome. Good luck.
Joe