Im not sure what the gearing is in the 800's but you could try a 1 or 2 tooth increase on the top sprocket.It will give you more top end..but less on bottom.Also your track may be to tight..loosen it of just until it won't rachet the track..i did this to my ZRT600 and it made a difference on top end.But if your studded you will have to leave it tight.