I got this from polar pro filters. It seems to make quite a bit of difference to the ambient and high pitched noises. The wind guard seems to resonate with the loud exhaust so it does distort like any microphone with very loud noises but the overall quality is much better.
oh yeah the car bit
, my exhaust is a full 2.5" from trubenz. It has a vibrant high flow cat, pacesetter header, moroso sprialflow muffler, and magnaflow dual exit at the rear.