I just finished putting together an Extra 300 with an
OS 160 fx. Is an APC 18 x 10 too much for that engine or do i need to go to an 18x 8
I am using the original muffler.

Thanks for your help

You can use either propeller. It all depends upon the type of flying you'll be doing, and how you want the airplane to perform.

G'day Mate, I'm running an OS 160 FX & I find that a good prop for my Katana is an APC16x10. I have tryed a 16x14 & an 18x8 but the 16x10 is the best for my setup. This arvo I was doing knife edge circuits, was great fun.
Good Flyin Mate,
Allan.