Vic,
Looking at this pic of your project:


are you going to be able to keep the exhaust enclosed within the cowl with only the end of the stack protruding? I was looking at my Saito 1.20 and 1.50 last night and it looks like it's going to be quite difficult to keep the original Saito exhaust concealed withing the cowl. I might have to do some modifying to the exhaust tube or better yet try to find some flexible exhaust tubing.