okay, on all the 4 mills with stock type cylinders they run pwk 35's. The 4 mill cheetah bike has a 38mm lectron.
Another interesting fact that defies the laws of reasoning is: In 1993 I took 4th place in the modified 350 class at Sandfest. My bike I ran had stock carbs bored to 27mm, and a set of FMF Gold Series pipes. Ultimately I lost in the 3rd to last heat from a bad start and still almost caught the guy at the end of the track.
So, I think high hp and dyno numbers play a factor, but biggest thing that makes a bike fast and easy to ride is your setup, and making sure everything you run works well with your portwork and other engine mods.
If people say that this guys ort job works well with certain pipes or carbs then you need to stick to that schedule. You sorta need to pick some pipes and carbs that coincide with your portwork. Or tell the engine guy which pipes and carbs you want to run, then have him do the porting based on that.