RE: GP RV-4 40 or a Sig SOmething Extra?
Yeah the .61 is a bit heavy but it's a great running 4 stroke.
I have an OS .45 FSR but it's in my old Midwest Sweet Stik.
My other motors looking for a plane to pull are an OS FP .40, OS Max-S .35 and a Saito FA-45 MK II.