I have a 2005 Horton Yukon XL 150#. My bolts are Horton carbons. When I shoot 100grn Thunderheads the arrow goes down and to the left. Not just a little. A lot. I even line up the vanes and BH blades. A buddy said I need to use 125 grn heads because the arrow spine is to stiff. What do you think? I want to use fixed blade heads. What is the fix?