I am installing a Saito 1.80 in a DP Ultimate. I am trying to decide whether to mount it horizontally or inverted. Mounting it horizontally will require cutting the side of the cowl which isn't very pretty. Mounting it inverted will also require cutting the cowl but it wont be as noticeable and will probably provide better cooling. If you have dealt with this, please comment.

I just finished side mounting my 1.50 in the ultimate. I did have to cut out the side and a hole in the top for the carb mixture and a hole in the bottom for the muffler. I used the stock muffler and cut a small piece out of the fire wall to give it enough relief to fit well. Its a 45 degree cut about the size of a 50 cent peice. Once the cut was made I used some fiberglass and epoxy and put 1 piece on both the inside and outside of the firewall. The mount doesn't look that bad from the front or the side. Those Chrome heads look good The only thing is the mixture adjustment is long and I had to cut a bigger hole than I would have liked to get the cowl to come off easy enough. Hope this helps. I like the side mount when starting it seems easier to get at the glow plug.
Jeff

i built a 120 and a 40 size. inverted the ys engines and everything fit perfect. makes the planes lines look nice and clean also. i believe it runs cooler too.

I side-mounted my Saito 150 and used an exhaust extension to hang the muffler off the landing gear. The cowl carving was long and complicated, but looks fine; notching the bottom of the cowl for the exhaust extension also took time, and looks okay. If I were doing it over, I would invert the engine and use the stock muffler, and install on-board ignition. In fact, I may just order a new cowl and do that anyway (but with a 180)!