ORIGINAL: Tired Old Man

I duuno, I'm interested in the performance, but not in the expense or time and labor involved for correct tuning. I prefer flying time to bench running time for personaly flying. I've seen the damage that can be done to an engine using incorrect pipe lengths. That fails to factor in incorrect header pipe, can diameters and lengths. I have plenty of pipes and cans to play with if I wanted to but practicality indicates that using a larger engine provides a longer service life for the power required. At least as it applies in my applications. Hobbyists may have a different outlook siince they usually hit the ground long before engine wear matters.

You can do all the math you want but you still end up playing around cuttting experimental pipe lengths. Engine in, engine out. Or do it all on a bench and not fly at all.