Brian, you might just have not bedded the pads in incorrectly. Common in race pads. I have installed new PFC pads and gone out to qualify and had the wheel shake so bad I thought a wheel was going to come flying off. Take some Scotch Brite pads and buff the rotors. Go back out and warm up the brakes with a few moderate stops followed by a couple off theshold braking stops and then let it all cool down. You may find thats all it is. A friend of mine who liked Hawk pads tried a set of PFC in his Miata and had the same result and just assumed the PFC are no good. He just did not bed in properly. Hope this helps.
Chris Howard