I know it can be calculated, and I have the software to do that as well as the theory behind the software. After all the general equations are not that complicated. Yet, the resulting constructions may need a lot of modifications to suit a particular engine best. It is not unusual, to enter the race track with a basketfull of tuned devices, and ending up giving them all to eager youngsters who want that racing pipe or tuned Helmholz device more than you do.