Compression, cam and ignition timing and exhaust pipe diameter can all affect the sound. If any or all of these are way out of bounds, a good engine will sound like a log truck without a muffler, just a ragged nasty noise. With larger cu. in. blown engines esp., camshafts are built with more duration (and more, and more, and more) LOL This is largely an effort to bleed off torque, at lower RPMs because these engines make so much torque that they require multi disc slipper clutches, or torque converters with little or no multiplication. These are things i've learned the hard way and at considerable expense. Please don't believe that I think I know it all, probably just enough to be dangerous. Anyway, I don't take myself too seriously.