If you shoot 125 grain heads with 60 pounds, the 5575 arrows will probably be spined to small. If anything, stay with the 100 grain head and shoot 100 grain muzzys. You'll have the same speed. The kenetics you gain with 125 grains will be very minimal, and it will screw up your FOC. You could turn your poundage up to get a little more speed and kenetics, but its probably on big deal. Id say stay with 100 grains and shoot 100 grain muzzys.