I've got an '07 WR 450, free mods done, grey wire cut, throttle stop and it's been jetted. I love my bike and think it runs exceptionally well. I jumped on a buddy's '05 "other brand" 450 and was absolutely blown away with the power of his bike. He was also shocked at the lack of power on my bike as compared to his. Both bikes are stock with free mods done the only difference is that his had a Pro Circuit Ti4 pipe and header. I know the exhaust argument has gone circles around here but will a pipe and header TRULY make that big of a difference? Anyone ever do a dyno comparison? Thanks.