...at least I think it's silly, but it's been bugging me. Every time I ride over a bridge, or overpass, or similar structure, my exhaust takes on a high pitched, sort of whistling sound. It does this without fail and without regard to wind speed, my speed, etc. I'm assuming it's just the wind hitting the ends of the Rinehart pipes and making a sound like blowing into a jug, I just find it interesting that it never fails.