I see. That makes a difference as a few of the areas that would be addressed on the older proclimb have been upgraded already on the new mountain cats. And you don't have electric start, right? If you did there are big savings in the tank and seat. If not then your stock tank is already 9lb lighter than say a stock tank on a 2012 or 2013. Stock 2018 tunnel, shafts, and skid are all about as light as you can get without some major chassis re-design.
My list for weight loss only on a new mountain cat would be similar to what CO said in the ascender section: Polaris gripper skis, can, hood/headlight delete, strip panel foam, strip idler wheels, smaller tail light, no snow flap, no mountain strap, belt drive, conquer 280 track will save you 10lb but the 3" powerclaw performs so well I'm not sure it would be worth it. That is all the cheap, easy, bang for the buck stuff. After that it depends how much $/lb you are willing to spend. You can get Ti runners and hardware for the Polaris skis, Ti handlebars, Ti bolts all start running $2-300/lb.