Ok guys, I need some help. I read all the info on the forums and went ahead with the NBS master cylinder upgrade. I have a 1988 GMC C1500 5.7, 700r4. I purchased Dorman M630031. I bench bled it and installed. I also installed all new brake lines in the front and rear, also replaced both rear wheel cylinders, brake rotors, pads, wheel bearings, rear brake shoes. I also bypassed the abs module. I bled everything again. Brake pedal is definitely firmer. No more sponginess feel. However if you do a panic stop, the brakes will not lock up no matter how hard you stomp on the brakes. I went over everything again, re bleeding etc. Still won’t lock up the brakes under hard braking. I’m stumped and look to the GMT 400 group to put me in the right path.