I have dynoed with that exact same muffler Dynomax SuperTurbo 2" in and out model wk17730 and then disconnected the exhaust and dynoed again. No gain in power, no loss.

160hp and 157tq btw. With just exhaust and intake.

The Ultraflow flows more but the ST in a bargain. It took 4 years for it to rust out. I picked up a new one yesterday in a 2.5" model wk 17733 to do my new 2.5" catback custom mandrel single exhaust.

I have a 1998 SE.

Also from the Dynomax literature, a pair of 17730 will flow without restriction to 236 actual HP and the ultraflow single like DemonSVT flows 260 actual HP. So I see little differnce according to the Dynomax manufacturer.

Correct me DemonSVT. I look to your opinion for most of my mods.

98 T-Red Contour LX V6 Mtx 106k miles
9" K&N, Aussie Pipe, Dual Mode Damper, 19lb. injectors, SHM MAFterburner, Ford 9mm Wires, Mystery Mod, ShoShop Off-road Y pipe, Dynomax Resonator and Muffler, 2.5" custom cat-back.