Clutch work and different weights

[Jayme Duty]

Ok guys, new here, this is my first post. I have a 2008 griz 700eps-se. It is completely stock except for 26in ITP's. I plow lots of snow in the winter and the bike now has 4500miles. It has very little low end power in high gear. i initially thought that the belt was slipping but after reading for a while i am thinking that i need new rollers. It seems that lots of people like to switch to the stock 450 weights. is this a good idea. also i read about getting a 1.5-2mm shim and that would help give me more low end. I never did figure out what would be shimmed, i was guessing the spring in the clutch to make it stiffer but not sure. Also is there a better spring to get for better low end. I plan on getting 27in tires also and i don't usually go fast, so for me the lower the better. Any advise is greatly appreciated.