Firstly, lets add Base Attack Bonus: +5 to the prerequisites. Higher if you think it necessary, but I don't.
Now, Piercing Arrow. Hmm. I definitely want to say we should limit this in some way. A move action to line up the shot?
My issue with Perfect Shot / Furious Arrow is that the need for a Concentration check kinda comes out of nowhere. There's no real reason to even be boosting Concentration except for this ability here. Now what with Storm of Arrows, there is precedence to make it a rage-ender. End rage, auto-crit. Maybe with a bonus (critical multiplier increases by 1 for purpose of the shot, so x3 becomes x4 and the like).
Everything else seems pretty sweet!