I read your guys post about the speed lost between a 80% and a 65%
letoff, just how much speed would I lose between a 80% compared to a 65%
letoff? Set up the same way. Frankly I like the idea of 80% letoff, the reason
is I was holding on adeer this year for about a minute and I started shaking
it was cold out plus excited, but that 80% letoff would of been nice then. The
justice I ordered comes 80% lettoff, just wandering if I should get 65% if
there is a lot of speed lost.

It depends on the individual bow. Generally most bows will be faster at 65% letoff, however that is not always the case even when draw lengths are exactly the same. Depends on how the module or cam is "cut".

That said, I would say a good average would be 4 FPS. I've seen up to 8 or 9 or so, but generally is between 3-6 FPS.

However, your Justice will be adjustable to whatever let-off you wish via the draw stop post.