I'm not a gearing expert, but the gearing sounds kind of tall for that track. Stock track has a much lower lug height if I remember right. I had stock weights in my 600, but with a spring with a total force of 114 kg, don't remember the colors right now. And a 50/38 helix and a green spring wrapped at 70 deg. With the stock helix it would overrev like crazy. My sled is also the european version, which is red, and has a different clutching. (Had to change that). My run was on river ice, with just a hint of water on it and several plus degrees, maybe 6C. If you want to go crazy with it, get ahlod of a set of 8bu weights, hauck orange spring, 20/40 gears and a 45 deg helix and a hauck silver spring, and then go and drag. I tried that set up on my MM, and I had to let go before it flipped over me. Engages at 5500 rpm.