Before i sold my XCR 600, i put plastic skis on them. I weighed them. The stock steel skis weighed 12 lbs. each so thats 24 lbs. total!!! I put on some polaris composite skis and they weighed in at about 6 lbs. each. So by simply swapping skis you've removed 12 lbs. off your sled! Not only that, but they usually perform better too.
I highly recommend getting rid of steel skis. Oh, i paid $100 a pair at Haydays.