Allen I've two bikes running this x-pipe and really like the power but hated the loud and put a kit muffler on each, which hurt the power some, but not really tamed the noise. Both my engines are highly modified 66 cc reed motors, but I tried one on a pure stock motor and it really brought that engine to life and I think it might be the best performance mod one can make on a totally stock kit motor. The carb might need a tune to prevent running lean with the x-pipe.
After watching the test video I'd say the results seem quite believable. The greatest benefit is in the low to mid power range & the dramatic difference in zero to twenty time tests clearly show this. Top speed increase isn't that dramatic on a stock bike, but the pipes value on a highly modified bike is really noticeable on top speed, which has more than double the h.p. of a kit motor. More horsepower allows the engine to get up on pipe sooner and helps push the engine through the 7,000'ish rpm bottleneck that stock bikes struggle against. I've built some highly modified piston port motors that had the same problem, though they had a lot of power, but adding a decent expansion chamber freed them up to blow right through the bottleneck and rev on to 11,000 plus rpm.
The best x-pipes are those made from small 2-stroke motorcycle x-pipes, but that's not what we're talking about here. In my opinion the pipe Allen suggested is the best x-pipe for the $$ that will bolt up easily to most frames and produce significant low to mid range power band improvements. I've wasted a lot of dollars on x-pipes over the last decade and this is the best one I've found...again working in the parameters previously stated and I bought mine from two different vendors than the one doing the You tube test.
They are crazy loud though and I added mufflers to each, which I'm sure effects the power band, but acceleration is still great even using a 38 tooth final.
Rick C.
