Have any of you guys ever tryed to increase the size on the carb venturi and opening the exaust, I did and I got 8300 rpm's on a 15x6 master airscrew prop flying it on a giantscale's edge 540 flys great, so try these changes and let me know if you can get the same improvement in power as I did. I enlarged the ventury to .400 inch diameter and drill a 3/8 hole through the exaust .