Hi Gary,

Although I haven't flown one, I am 2/3rds through building one. I had the same thought as you and thought were they actually needed. After speaking to my CARF rep it became pretty obvious that they are because without the NACA inlets there is no way for any cool air to enter the gap between the inner and outer pipe. This is because the carbon bellmouth is a snug fit in the hole in the former.

I decided not to take the risk and cut the fuselage as per instructions.

Geoff.