This is by no means the way to go, but maybe some options.
On my mostly stock SVT...I ran the stock mufflers, but got rid of the main cat and the resonator and put a resonator/glasspack (whatever you want to call it) it sounded good and I don't think I needed anymore flow than that.
I have a 3L trubo now, no cats, no mufflers, I have 2 3in resonator/glasspack's. It's a little louder than I would really want, but it sounds pretty mean.
What I have found is that Summit exhaust parts are very high quality and good price (they are actually made by a reputable company, but they don't say who) I kind of think it might be dynomax.
I have one on my wife's Exlporer and it sounds really good not loud at all.
Then from my mustang friend I have heard that the dynomax ultra flow are the ones to get for maximum flow and least noise.
I still don't know that you would need a 3in exhaust, but good luck. If you are worried abotu quality and price you could always have a cheap system made and then when you found out you liked it then have a nice one made. Then you eliminate a lot of the risk.
