Ok, here's the newbie coming out....

My OS 91 surpass has a nipple on the muffler that I think pressurizes the fuel tank.

I'm building a second plane (also a four star 60) and have a cheapie K&B 65 sportster that I want to use. There is nothing on the muffler to pressuize the tank. In this case I assume I have to run the vent line from the tank out the bottom of the plane.

My question is... Should I do this on a 4 Star 60? Does it effect the engine when flying inverted? My trainer has an OS 40 LA which also uses the muffler so I don't have any experience with the other type. Any advice to go this way or not would be appreciated. Thanks.