Well I tried an APC 20X8 and only got 6000 RPM. I think this is low from what others are getting on the forum. I''m using a 13.5 mm carb and I drilled out the stock muffler. The engine starts ok and idels and transitions very good, but no RPM[] Any ideas? I''m considering going gas/glow if I can''t improve the RPM. It is a LE (low emission) model. I wonder if that makes a difference?