All my OS's have been great .25AX, .25FP, .46AX, .55AX, .75AX, 40FS, 110FS. All except the .95AX for some reason its a lemon, other members at my club have also stopped using them. They seem to overheat even with adequate airflow over the head, i always thought i was getting fuel foaming, but the latest fuels have anti-foaming stuff in them.