RE: Home Made Canister Mufflers?
Understand - the BIG difference is that motorcycles are setup with torque multipliers (gearboxes) and and this plus a whole lot better carburetor setup -really changes the game
Also the relatively small passage sizes we have- makes a lot of difference in flow
Technically it has to do with air attachment to the confining sizes ( tubes/passages ) so relative flow to size changes .
Once when I was learning about fluidic control systems (a very limited field) the setup information stated that I should use X diameter tubing for X number of valves (these valves simply switched paths by diverting the column from port A to B - then it stuck there ) and if this didn't work - double the size of the supply lines -- (cut with a lazer then trim with a chainsaw)