I have a 2001 800XC and a 2002 800XC.
I added PSI pipes and some clutch modifications, boost bottle had the 2001 punched out to 875 cc.
(All before I bought the 2002.)
I am very impresed with the low and mid range response of the 2002, but the 2001 lacks low end response.
I had a flat spot in the mid range between 5200 and 6200 RPM but I changed the needles and that area is fine now. I rode with a friend this last weekend and he has a 2001 800XC also with clutch work and boost bottle. He has the V Fore reeds and his low end response is similar to my 2002. I'm thinking about putting the V Force on my 2001. PSI wants $400.00 US for their reeds so the V Force sounds considerably better. If I get this done this week end I'll let you know. By the way I'm not a new rider but I can't figure out how to elimnate that from my profile. I first rode a snowmobile in July of 1972, but that's another story.