I have mine in a Mayhem which is more of a 3-D plane and run a 16x4 APC. I also run a 15x6. A friend has one in a 4*60 with a 15x6 APC and it performs great-probably more what you'll want in the Mustang. The RPMs run in the mid to low 9K range, which is the number i always try to hit on 4 strokes.

My 110 was orginally going into a 60 size Corsair which is almost complete but didn't like the muffler, so i swapped a 110 YS out of the Mayhem to go into the Corsair. I too would like to run the OS if i can find a simple smaller muffler.

As far as fuel usage (it sips the stuff) and not much for oil all over the plane unlike the YS. You don't have as much power but for a Warbird in a 60 size it should be great. It flat out rips a 4*60.