thats for the imsa cars, that setup is 2x42mm pipes, they collect somewhere around the rear axle (230mm long), and then theres that collector and megaphone tip. its super duper loud, like you can hear it across the paddock DURING a race loud.



might be a good way to go from one size pipe to another though

 

thats not how sound works, its irrelevant in fluid dynamics. The (mega) (phone) is called that for a reason.

 

Im hoping for 150's at the highest, but Im expecting 130's to 140's.