Powersticks
I'm running a pair of the longest 2.5" powersticks on my 318 Duster. They sound great, nice and loud at idle and when you hit the gas they've got a great roar to them. The nicest thing though is that it quiets down significantly around 55 MPH, so cruising on the highway is no different than when I had single exhaust and a cheapo Sears muffler. I posted a clip of my car in one of the stickies if you want a better idea of how they sound.