Scott, I have a os 91 4 stroke in mine and I just cut out the fake engine so that the head of my engine showed plus I put a large hole in the bottom of the cowling to let the air out and to have access to engine adjustments and fueling. I've had no problems with this setup so far. I can say I was pleased with the quality of the kit and other than two clicks of trim my plane flew hands off on the maiden flight. I mounted the battery on the engine mounting box in order to get the cg as listed and I think its gonna be a great flyer after I get used to the plane.
Bob