Well, as I said I was less concerned with the "custom" tuning of the pipe than I was with getting it to mount securely and routed where I wanted it - But I'd say I took perhaps an inch off the elbow and 1/2" of the long J pipe.
The exact performance increase for my 66cc 44t is difficult to tell you as it was mostly acceleration, my 0-30 improved noticeably. After I readjusted my fuel-air mix to compensate it ran better on this pipe too.
Unfortunately I didn't set up a 1/4 mile drag run (1/8 mile? lol) in retrospect I kinda wish I had. With a buddy and a stopwatch I could prolly figure the acceleration difference. I do have an almost perfect 1/8th mile section on my way to work - but w/o that stopwatch all I can tell you is I picked up a healthy 2mph.
This doesn't accurately reflect how fast I got to my top speed though...
It may not sound like much - but little will effect the top speed of my bike, with the 44t @ 33mph I feel it's close to redline. Yet acceleration is more what I'm interested in anyway. I will say it's not a "peaky" powerband - it's well spread and usable.
lol - I hope someone does
break out a stopwatch for a "before and after" but sadly - I haven't even someone to race. I'm the only motorized bicycle around here and the local mopeds are a far too easy prey