JARichard, I have an'03, HO, 4X4, 6-sp. Your system should be 3-1/2" from the turbo to behind the muffler into the tail pipe where it expands to 4". I had read that if you place the free-flowing muffler right behind the down pipe (under the shotgun seat), you have less chance of getting the drone. What I did was go to Muffler Dealer's Whse. , in Gilbert AZ. and bought a Magnaflow 24" muffler #MAG 12772, along with a 3-1/2 " to 4" transition (reducer) #MAG 15441. Muffler was $68. 44, transition was $13. 25, =$81. 69. The muffler shops in town wanted $125. 00 just for the muffler. I took these items to Pro Muffler in Peoria, AZ. Muffler installation was $30. 00. He had to buy a 10' length of 4" aluminized pipe for between the muffler and the tailpipe section. That was $50. 00. With tax it was $84. 65. Total price was $166. 34. I've towed to Las Vegas with it and driven around town. Haven't noticed any drone, at all. Has a bit of a "B-R-R- R-A-A-P-P, sound to it at 1800-1900 rpm's. The Aeroturbine seems to have a harsher sound. This is more mellow. Doesn't quite sound like a diesel, though. I find I drive withe the windows down just to hear the muffler. Joe Donnelly wrote that He liked the sound of the Allied muffler, the best. Hope this helps!