What prop to start with?

[Jabbo]

Looking at getting an ammo 36-50 2300kw and a swordfish 120 to run in my fastec 27 I will be running 4s what would be a good prop to start with?

[sailr]

X438 or X440.

[Alexgar]

stock actually runs pretty good and no nee to balance

[Jabbo]

Sailr just to let you know my velocity mono is running great! It's a blast!!
Also where can you get those nuts to hold down the hatch I know I will lose that little thing eventualy.