Mine feel the same w/a manual CPP disc kit and no air, no leaks. The pedal initially feels too soft compared to what I am used to in modern power braking. However, I am able to lock em all up if I push the pedal firmly and in casual stopping if I pump it once pressure builds and I don't feel like I might need to stand on it while waiting for the light to change. This happened with the CPP and POL Corvette MC as well as the CPP Mustang type MC I am currently using. I don't know how much of this is simply because they are manual brakes (my buddy's '52 F1 feels the same with a similar manual kit) but have noticed a significant amount of flex in the CPP/POL MC bracket which may be causing some of the issue. I was considering adding an additional gusset to the bracket as well as switching to steel braided soft lines to see if that helped.
The residual valves actually keep the MC from siphoning the fluid from your calipers/cylinders when your MC is located under the floor. If your MC is in the stock location, you should be using a 10lb valve on the rear and a 2lb valve on the front. This is important when the truck is lowered, in my case, the MC is below the calipers but even at stock height it can happen on an incline.
