If it's not too late, buy 8 tooth anti ratchet or no slip drivers. Micro Belmont in Grand Rapids MI has them. Yami's always require a pretty tight track or they will ratchet. I put 8 tooth no slips in my 780 viper and they are amazing. One of the best mods I have done. You only need two of them not four. Without question, I will not own another sled without them. As for gearing, I went to a 136 ripsaw, and geared up 2 teeth on top sprocket and am still getting huge MPH for that big track. I am seeing nearly 130 on speedo on half mile runs. As for studs, I would'nt go more that 1.375's. That's what I have and they are tickeling the tunnel in a few spots. Partially because I can run the track so rediculously loose it was slapping at the top of the tunnel a little. Good luck, FYI, you will have around $150 in to the two drivers. Don't let a small dollar amount sway your decision. For less than $100 difference, it's the best money you could spend.