Tune:
a pipe is in tune when the length of it allows the beginning of the return baffle wave to reach the piston just as the transfer ports are closing. This is true for whatever powerband a pipe is designed for.
Powerband:
divide the peak rpm by 4 and that gives you the rpm at which an intake boost starts to happen from the diffusers return suction wave. Steeper diffuser angles give a stronger return wave. The baffle angle counters the suction wave at all rpm below 83% of peak rpm. So as you design for a stronger baffle wave you accept that low-mid rpm power will be reduced and peak rpm power will be increased. For one speed street engines you want all the emphasis on the diffuser wave, and a weak baffle wave. That can be accomplished by a steep diffuser wave and a baffle wave weakened by having a shallow angled baffle cone, or by a 7-10 degree baffle cone split in two and elongated around 4 inches. Any of yall with a store bought racing pipe (which they all are albeit of no use to you low rpm zingers) can saw it in half and then weld in a 4 inch long cylinder of the same diameter. That gives a longer return wave of reduced strength that affects a wider top rpm range without overly countering the diffuser wave.
The pipe I have for sale will be in tune for 5500 rpm if the header is around 15 inches long. A shorter header is for higher peak rpm.
