I have an 08.5 GT500, 28", 60#. I've tried the arrow manufacturers charts and OT2 software. I get different results. All of the arrow charts say .400 spine arrow, but OT2 says I'm weak. When I try .350 spine, OT2 is way too stiff. My current shafts are PSE radial X .300 26.75" long. Wanting to try one of the newer small diameter shafts, but can't find anything on OT2 that works no matter how long I cut the shaft unless I go with 125gr bh or 21 gr nocks. Need some advice. Thanks!