I use a 16x10 on my 150 size H9 Mustang with Saito 180. I read in a thread here on RCU that a lot of guys said the 18x6 would barely fly the P51. Most were either using a 17x8 or a 16x10 APC prop, I went with the 16x10 because I had one and it flies great. Lots of power and speed plus slows down good for landing.
fossil