I ran them on my 04 Low rider with carb. one of the guys i ride with is running them on his 06 wide glide with fuel pak has not had any problems. The first time i changed mufflers on my 07 SERK i went with the Fuel Pak, Ran it for a couple months then trash canned it, Went to PCIII, And since changed the complete exhaust and added Arlen Ness Big Sucker and have not touched the PCIII, It runs just a little on rich side but seems to have cooled the motor down a little. Because of it running on the rich side the gas mileage went from high 40's to low 40's sometimes high 30's and thats riding 2 up just about all the time. I tried to come up with a way to put Big Radius on my SERK, I called V&H at the time they told me they had no plans for the Big Radius to fit a bagger so i bought the Big Shots then a few months later they came out with the BR for a bagger, Man was i P Off, Thinking about changing the B. Shots to the B. Radius by this spring, I think they are the best looking and sounding pipe on the market.