Lowering the intake was the same as cutting the piston skirt but you could go 2 more mm on that but it may slow your low end more. With 50cc you are always dealing with a low/high end balance and that you weigh exacerbates that dilemna. I checked the performance of a bullet and a Homoet 6p back to back on a hot 50 and the 6p was only good for about 2 mph more. If you were to do a compression test what would it come to? You could shorten the Bullet at the header and or the dwell section of the pipe for higher pipe RPM action. The header on these pipes extend 2 and a quarter inches into the expansion chamber. The 6p is about 2 1/2 inches shorter than the Bullet. An auxilliary center bleed welded onto the Bullet will help. Use maybe 45 psi or more if you have good tires to compensate for your weight.