petrol, What kind of performance/speed increase did you see with the rejetting (size from/to?), exhaust and air filter?
I'd say the muffler itself gives you a slight increase in top end power. If I remember correctly, my Super 8 would top out at 54mph on the GPS before the Two Bros. muffler and 57mph after the muffler installation. I didn't have to re-jet the carb after installing the muffler BUT I did re-jet from the factory 103 size to a 110 size main jet long before I installed the 2 Bros Racing muffler. My first re-jet had nothing to do with performance though. I re-jetted the carb because my Super 8 would bog down big time when the engine was cold. It ran great when the engine was all warmed up but I hated waiting for it to warm up so that's why I re-jetted.
I installed the UNI Filter about 2 weeks after installing the muffler and I was able to hit 60mph on the GPS for a brief second the other day. I did have to re-jet after the installing the UNI because my Super 8 was bogging big time during full throttle. I went from a 110 main jet to a 125! I was so surprised that I had to go up 15 sizes to reach the correct jet and I was a little pissed since I had bought a 112, 115 and 118 size jet to try and fine tune the carb but it was just a waste of $25 bucks since I used a 125 that I had laying around.
Also, these speeds were achieved on flat ground.
