I have a built-in bias but if you've never heard a crossplane crank R1 with a full system, you're missing out. It sounds like nothing else on two wheels, more like a V8 than an IL4. Sounds great down low but still revs to 13,000+ rpm! BUT, I only ride that bike at the track. To me there is nothing more annoying than a Harley/metric cruiser, raging through downtown with straight pipes, echoing off all the buildings. Same for a sportbike (usually a gixxer or ninja, any displacement) with a rat exhaust shrieking around town. Loud bikes seem to always get the "do-gooders" busy at the legislature. In the right context, I love the sound of a well modded exhaust. In the general public though, "loud" usually works against us.