My son just bought an '01 ZR 600. The secondary has an aftermarket helix, and I imagine the primary has been messed with as well. The p.o. didn't have it set up very well either so we're going to just return everything to stock. The Cat website lists several helix angles and primary weight options, (relating to altitude I imagine). Here in Minnesota we're at about 1,100 ft. Anyone know which angles and weights would be the right ones?