rcjake, I see your pictures and I can only say that I did mount it directly to the firewall and the cowl fit perfectly as well. Here are a couple of pics. I can't remember (senior moment) but I might have mounted it that way so tail weight was not needed. It is a heavy motor. By the way, the Saito is 27mm longer than the OS. (148mm vs. 175mm) A little over an inch.