Steve,

Both of mine have the plastic insulator on the front of the pump. I have used and APC 17x12, 17x13 and an 18x10 PN. The 18x10 is my preferred prop for pattern. For me, the plane flies at a much more consistant speed for up and down lines and thru out the entire sequence. With 15%CP I'm turning 81-8200 rpms. Hope this helps.