Several years back, I bought (from Branda I think), an aluminized factory style stock system for the GTA; H-pipe, tranverse muffler with two resonators. It has a bit of the Bullitt sound to it, but milder. The Hi-Po has 3 chamber Flowmasters and definitely growls and has harmoinic resonations. The problem, with with my ears, is that they don't hear the same as yours. What's good to me may be unacceptable to you. If you could listen to some already installed systems you would be better able to decide.