Mine started easily and ran smoothly on the ground just as it had done on the bench. I tried an 11-4 prop and got about 9500 rpm and a 9-6 only 11,000. I could not get it to idle less than 3000 rpm. Mine would die after 3-5 min in the air. I think mine needs more break-in time and a cooler plug (I used a Fox Miracle)
It may be fine on .20-.25 size planes but it was too wimpy for a 3.5 lb fun fly. I removed it from that plane and didn't have a plane appropriate to use it.