1st I do not propose anything, it is proposed by the pilot or sponsor portfolio.
2nd If an engine is well prepared and who carries it does not pass the account does not have to break.
3rd About the retention of exhaust gases in the silent ones I could tell you that after building a few in stainless steel, the simplified formula to find the most appropriate diameter to the tube is as follows:
Lc = (13000 x ge) / (rpm x6)
Where:
Lc is a length of the collector (if we stretch it)
that
the crankshaft is maintained RPM is the maximum regime to which it cuts on. I do not think it serves as much to put you tooooooda literature or toooood the theory or toooooodes the books that I have read to know what I know.
I agree with you that you are not putting a silent "remus" brand or "powerful" or making a lot of noise so that it is more tunning. It is to know where the dimensions of an engine come from when designed and where you can get hand and where not.
I hope I have clarified some lagoons.