The king cobra is def a good clutch. Pedal effort shouldn't really be much if any worse than stock. the frpp heavy duty is the exact same clutch, same holding power, just a much stiffer pedal feel. Most would hate it. I don't know about using the King cobra on a 300 hp car though. It's kind of a boring clutch. it's good enough to not slip, but soft enough to where shifts are boring and it doesn't slam like a spec will. However, that's probably a good thing for the t5. I wouldn't touch the stage one specs, or the stage 3's. Stage ones are very prone to chatter. From what I hear, the stage 2's are not as chatter prone, but I only have experience with the stage 1, so I can't verify that.
I'd personally recommend the centerforce dual friction. It will grab hard, but not as brutal as the spec, and it will hold more power than the kc clutch. I love my bro's centerforce clutch, pedal effort is lighter than stock, and it grabs great and hard, but not too hard.