I'm just a hair under 650rwhp and running the ACT clutch. The price is right where you are wanting it to be, but I wouldn't just replace the clutch while you have it pulled apart. RAM makes an upgraded Billet slave cylinder that should be on your list as well. The factory slave is plastic and the extra heat that gets generated with the extra HP can lead to issues.
When i replaced my clutch, my slave crapped out about 4000 miles later (technically it melted, but you get the point). After that I had a leak in my bleader line. Both issues sucked and I thought I was going to have to replace a brand new clutch. Not a good feeling. Not to mention the $$$ involved with pulling the trans out multiple times.
The pedal feel is much stiffer than the stock clutch feel.
UNDER CONSTRUCTION. ETA 2016 ish...