THat is what I have used....
That prop out pulls anything else on that engine....
Had a 16x8 xoar.... not even close to the apc 17x6
Mine was piped. Went like stink!..
The regular muffler didn't have the high end the pipe had, or the rpms...
Apparently it works well with it on std. muffler...

I wish I would have had video of it on my 69" yak....
Looked like a 50cc gas engine...

I had a dud os 1.20 ax, and it didn't do as well as I had hoped with that combo..
My replacement, was never flown with out the pipe...so I not sure how it worked
with out it...