I posted in another place on this website, thought I might try here also. I have a brand new '07 YZ450 and I want to do a hare scramble race in two weeks. My hangup is that we are required to run a spark arrestor and I don't have enough cash to put an exhaust system on my bike. I was wondering if anybody has tried the Pro Moto Billet Spark Arrestor kit yet, and if it helped or hurt performance? It looks like a nice piece, but I don't want to spend $130 that i could be saving to get a new exhaust if it's just going to hurt the performance of the bike.... Thanks for the help!