I agree with the Boss K. I shoot a BowTech Pro 40 at 295 fps and use 125 grain, 2 blade, Stingers. If the bow is properly tuned, it should shoot anything straight that is perfect to begin with.

I am sending back 2 Stingers for replacement that were not flying true. Probably my fault for driving them into 2 X 4's but hey they have a lifetime warranty.

Nothing wrong with your set-up. You know that those Thunderheads work great. But if you want to try something new that puts one heck of a hole in em, I recommend this mechanical; It�s the Wasp Jackhammer. The cutting diameter is 1.75 inches and they are durable as heck. My friend has shot one into a 5/8 inch piece of plywood several times without it breaking.