I just posted that my sbp exhaust gave me incredible low to mid torque, a real hill puller but I'm sure I lost some high end. I'm not certain high much I lost because I swapped out sprockets also.Well, I took the bike out today with the SBP expansion chamber.
I dont know how I feel about it yet. I wasn't expecting the degree of quiet It has. it also falls on its face in low RPM at 3/4+ throttle input. once its kicks in though it has a great tone and finds its stride. Seems to have lost 6-9mph top speed.
I shortened the header on it and we will see tomorrow if i miss the rain if that helped
The low end is so strong I can pull a pretty big hill by my house from a dead stop no peddling and about a ten yard head start with no issues.
Does your motor have any other mods?
Dan.