I was also going to try and mount the mag91 4 st in it. Knew I'd do lots of remodelling in the nose area, just why is it to long? I'm not sure I see that yet. Read some reviews that had a XL-61RFS and found to be a somewhat non performer. Taking off that flapper valve looked like a area to get some room back, cowling is going to be an issue though. Are 4 stroke engines just a little underpowered for this plane anyway?
thanks,
Ron