Im thinking of making an exhaust and wanted to make a megaphone shape like a tumpet straight off the port and wanted to try and use the theory of the velocity stack basicly have the speed of sound travel from the port back to the port as the port opens back up but am having trouble getting this worked out sounds crazy I know. But when flying my trainer a couple of years ago with an os la the nut fell off with vibration and the end came off the exhaust during flyte but I thought it sounded pretty grizzly just above tick over and would love to experiment as I hate that screaming noise and those quiet pipes you can barely hear any help on how to maximize the noise and get the calculations for the velocity stack design also was at an airshow and was looking at a spitfire and the exhaust pipes were tiny is there a short distance exhaust pipe tunning formula