Sounds like it might just be a defective master cylinder. I'm not sure how the CPP system installs compared to the Master Power setup I have, but in the MP installation instructions (page 4 item 2), they specify drilling a new hole in the brake pedal arm 2.5" lower than stock.
http://www.mpbrakes.com/uploads/prod...STRUCTIONS.pdf
I ran mine with manual front discs for a couple of years before installing the booster, and the pedal was hard as a rock. With the engine off it remains the same today with the booster in place. It's been over 10 years since I added the booster so I can't really remember if drilling the hole lower on the arm made any difference in pedal feel.