1100 BUCKS!?!?!? Did they supply lube?! That's ridiculous.
Anyway, snjo23, you can check the pics of my old 90 in my signature. I had duals run behind the rear tires angled out a little bit.
The exhaust consisted of 2.5" pipe from each manifold to two tractor mufflers (metal baffles instead of fiberglass). I then removed the mufflers, cut them apart, removed the baffles, then welded them back together and back into place. From there, it went out the back into 4" chrome angled tips. It "sounded" like a monster truck, but it sure as hell didn't have the power.
If you do something like mine, be prepared to install a better sound system or some sound deadening material. It popped like crazy and pissed people off.