When an engine changes tune in the air, you are most likely seeing the air pressure in the cowl change and the carb seeing that change. It's a fairly easy fix.
I believe you are talking about the static pressure nipple that the Brillelli's already have in place. I have a piece of fuel tubing attached to it and running back into the fuse. The engine is not currently cowled.
What I'm finding weird on this engine is that I can really lean out the low end and the engine still runs great, but it seems that the high seems to need to be much richer. I've got the top end to where it doesn't sag at WOT and it's loading on an upline, but it wants to die in the air when going from low to high after a downline manuver. I will try richening up the low to see if I can get that to go away.
Thanks