I went with dual 2.25" run down the inside of the frame, where the stock exhaust was. Mufflers were twin Dynomax 2.5" turbos, mounted vertically together side by side. But I ran the exhaust all the way out the rear under the bumper. I also later added an equalizer chamber of my own design plumbed in ahead of the mufflers. The chamber was a 12" section of 4" tubing, with the dual 2.25" pipe welded into both ends. What it did was mellow out the Turbo's sound. Previous to this I had run the exhaust outside the frame with glasspacks and the pipe exiting forward of the rear wheels. I outgrew the sound of glasspacks.