Installed Magnaflow #12586 over the weekend, and WOW ! Removed the Resonator and Muffler, and had a filler piece made up. This paired with the Zabteck T/B, and K&N, has increased my Smiles per Mile by a Ton. It is just as quite at idle, but any input of the skinny pedal, and it sounds like it should have from the Factory. Overall i am now at 15.5mpg/city and 20mpg/highway. Up about 2-3mpg from the 91performance tune from Torrie. #12586 has the Center input and Offset output to make the install a little easier. Also because this is the longer 'quieter' muffler, i had to move my hangers a bit to keep it secure.