RE: GMS Engine??
I only own the .40, but it absolutely screams. Easy to start, and nice reliable idle-once broken in. It spins a MA 10/6 at well over 15K on PowerMaster 10/22 fuel.
Best of all they are DIRT CHEAP. Wait for a $20 off $50 coupon from Tower and you have a $40 engine that is hard to beat.