Instead of an SLP intake, we closed off the instrument pod area, modified the top of the air box, ran a flexible tube up and into the pod, and now use the extra tach/speedometer hole as the main intake with some frogzskin over it. We also made a couple more intakes around it. We deleted the oil injection with a block-off plate, bottle, and pull rope bracket from the snow cross sled. I think that was a $150 mod, but the tiny oil bottle was like $42 or something. You could probably find a cheaper bottle. Also pulled all the foam from the belly pans and removed idler wheels. Get the shocks rebuilt! We did that all the way around on his and added some more damping shims to the fronts while we were at it. Install new springs in your clutches as I am sure your old ones have lost quite a bit of their force if you haven't changed them in a while.
Right now his sled handles way better than any XP I have ever ridden. He is so happy with it that he is putting a TKI belt drive on for next year and is going to ride it for at least one more season.