I'm running a YS-91 in my TF P-47 ARF. I just did a straight pipe. I had a 90 degree header from Central Hobbies on hand so I took the flare nut off of that, discarded the pipe, lightly flared a piece of 3/8" steel tubing and installed it on the engine using the flare nut. I angle cut the pipe it so it just sticks out of the cowl. There is a small hole in the side of the cowl but nothing drastic.

You could also bend 3/8" steel tubing into just about any shape of pipe you want to exit just about anywhere.