I've ridden a 17 850 with an mpi turbo set at 200 hp for 3 years. Last year I had a silber 850 Freeride that was insanely fast! I ordered a 21 expert turbo for this year and was originally a little worried about being down roughly 40 HP to my last sleds. I thought about putting a tune in it before riding it, but ultimately decided that I'd ride it a few times and then decide. Yes, its down on HP compared to an aftermarket system, but its just soooo much easier to ride in the trees and technical terrain, which is my favorite thing to do. I decided to leave it stock, not even a can. Gas and go, no issues at all! No way I'd go back to an aftermarket turbo