I like TAg metals. I have thier handle bars on my quad and on my 450 I had a set of thier sprockets on it. they held up well And its diff from everybodys renthal or side winder BUt thier is a company out there that has a lifetime warranty on thier sprockets. I look in DIRTWHEELS i think they advertise in that.
Why would you want to put a 40 on the rear you are going to kill your top end . i was running a 13-39 for short tracks,arena cross and would pull the hole shot everytime but outdoor big tracks 14-38 and have all the power i can use.