i run a laser x-pro its suited for low revvin cylinders really, i run it on my stock cylinder ported and can get just over 60mph on clock and i beat every1 other 50cc around by miles, its better than leo vince rubbish, ill bre getting a low-mid race 70cc soon and trying it then. Been told a doppler s3r pipe or gianelli shot is the way to go otehr than the x-pro.
Saying that the pipe does allow quite high revs, i put a race 50cc kit on my bike which was high revvin, i has 10-20mph when the bike seriously flew the belt slipped and all but then this stopped and revs were back to normal and couldnt get the right setup witht he pipe-using super light rollers. But on a long straight road i got 70mph clock speed, using 2gram rollers (9 roller vario)