Are there any real rules of thumb for the length and diameter of a zoomie primary tube on a supercharged motor? For instance, shorter for higher RPM or bigger diameter for more displacement, etc....? Is there any sort of intent being made to generates a suitable reflected exhaust pulse, or is all of that irrelevant since there's 40+ PSI waiting behind the intake valve? Has anyone messed with stepped diameter zoomies? Or is it more just a matter of what "looks right" for a given application, and get the exhaust out as quickly and smoothly as possible?