Bob: I just about have mine finished. I put a Zenoah G-26 with the B&B single pipe header on mine. I have cut very little out of the cowl, only cut out for the header pipe to come out and i can bolt it on from the front of the cowl with the cowl loose. It really fits nice in it. This is one of the nicest arfs i have ever seen. Hope it flys as good as it looks. Ed