Guys, thanks so much for the responses. Mike, actually, I want to put a glow engine in my SU31 3D. Glow engines are what I understand (I know little about gassers). I was thinking the Moki 180 was also glow - maybe I'm wrong on that. I've actually seen that video and it looks like fun. Did you install a Perry pump in that plane you reviewed? I'll go read your review, perhaps you mention it in there. I would prefer to go the OS route simply because IMHO I feel like service, etc. will be easier to come by. As for the airplane, I am looking to do fairly aggressive 3D maneuvers with it - once I think my flying skills will allow for it. Also, on a related topic, from my research, it would seem the Slimline Pitts style muffler would be the way to go. Agree with that thought? Thx again. I'm simply trying to do this right the 1st time.