I don't know for sure, but DG may have one. Like you mentioned, it does make it harder to adjust the chain. My friend has one on his 300EX, and it seems as if it will do you more good than it does him(the little ones and all ).
2001 DS 650- Diamond G racing steering stem, Longhorn bars, Armadillo a-arms, HMF exhaust, jet kit, Trail Tech computer, and some other stuff.
Coming soon- YFZ 450 Pro-Pegs, CRF 450 rear master cylinder, braided lines, IMS 5.0 gallon tank, black plastic and seat cover, powdercoated frame and swingarm, HPR engine kit, Scott's Stainless oil filter, radiator shrouds, and much more.