I have just replaced the chain and Sprockets on my TRX 850 back to the original gearing (17F,39R), replacing 18F and 39R. I have found the bike shudders a lot more now on low speed take offs. But is an absolute dream on the freeway. It also seems to accelerate faster as if the gear ratio helps the bike use the torque to greater effect. I'm currently running JT sprockets I was thinking of getting an AFAM alloy 42 tooth rear(I have hopefully left myself enough adjustment in the chain) to maybe help with power wheelies . whaddya reckon ?