I am finishing up my 1/4 scale Extra 260 and it weights around 11-12 pounds. I am using an OS 1.60FX engine swinging an APC 16x10 prop, and it is producing around 17-18 pounds of thrust (according to my pull type scale).

My question is this, how much athority will I have to pull out of a hover?

Really using this aircraft for IMAC, but knowing me, I will be adding some 3D stuff into my practices

Typically, a 2:1 power-to-weight ratio is desireable for unlimited imac and 3D, but a 1.5:1 ratio stil ain't bad. If you are not running a pipe on that engine, though, you can expect degraded climbout performance, as 2-strokes are lacking in torque, especially without a pipe, and quickly excellerating that prop from hover throttle to full throttle is hard to do.
BTW, you may want to try a 17X8 or 17X6 to get more brute pulling power. It will also help to keep your downline speed in imac more consistant.

no pipe, bisson pitts style muffler.

ask 10 ppl what size prop to you, I swear I get 10 different answers...LOL

I do have a Zinger 18x8 I can try also.

and thanks for the input !

Bolly 19x6 is your best bet for pulling out of hover. It weighs 4 oz (lighter than the 5 oz APC 18" props). You can get the Bolly 19x6 from Desert Aircraft.

I went and got an APC 17x8 today. I wont be getting a bolly prop anytime soon... this airframe is for me to do IMAC stuff... just wondered about its 3D capabilities, for if/when/never get a 33-35% IMAC plane.

Expect 9400 on APC 17x8 prop. It will fly plenty fast. Pull should be adequate, but 18 lb is about as much as it will register on the pull scale. Please let me know what it pulls if you measure it. Thanks.