Position muffler for new-style exhaust orientation

Sling is now mounting the muffler, and spinning the tail-pipe 180 degrees such that it exits the bottom cowling in a much more horizontal orientation. They have indicated that the muffler should be oriented such that the tail pipe still passes 15-20mm below the engine mount. The distance between the tail-pipe and the bottom edge of the firewall should be 50-60mm.