Yeah no shit. The thing is, those supercars are insanely loud from factory. I was behind a pair of Diablo SVs in a traffic jam on the motorway once, and even then they pretty much drowned out the sound of the little 500 cc motorcycle engine between my legs. I have no idea how those things are deemed street legal.
Edit: It's not about the revs alone, but also engine load. 3000 rpm stationary might be relatively quiet, but 3000 rpm with the throttle blades wide open is an entirely different matter.
So you mean they're round.