1. A G38 was clearly outside the manufacturers reccomended engine range. The excuse was it doesnt put out as much power as a glow 1.8. Well, a glow 1.8 doesnt have the mass and vibration of a G38, therefore the firewall absolutely needed more support than was given. I would never <ever> put a gas engine on an unpinned firewall - EVER! Even JimRoss admitted as much.
A g38 is NOT out of range for the Sig 300XS, sig recommends the FPE 2.4 ( 40cc ) engine for this plane and shows the engine being installed in the instruction manual. The g38 (38cc ) may be a few oz more in weight, but the FPE 2.4 makes 10 more lbs of thrust!
FYI: he called sig before the install of the g38 and they gave him the go ahead!
ON ARFS: Very hard not to go with an ARF today, unless you LIKE to build. The business of judging each other over what type of plane you have is nonsense. I see it all the time, even at my field....." is that an ARF???" .....YUP, ......Oh, guys it is an ARF. I am the best pilot at my field, I do not have one kit built plane in my hangar at this point, most of my old timers have now switched to ARFS.
We make changes to kits, we make changes to ARFS..............has a firewall NEVER came out of a kit built plane???