I added C5 front calipers and C5 rear calipers w/ LS1 rear rotors to my camaro. I changed all the rubber lines to braided lines including the rubber brake line that sits on top of the axle housing. The brake pedal is now too firm when stopping as if the brake booster is not helping me push the pedal all the way to the floor. I do not get much pedal travel at all. Pressed fully down the car does not come down like it should with C5 brakes. It should stop much harder.

The LT1 brake booster should be strong enough to work with C5 brakes.
Is there any difference between the LS1 brake booster and the LT1 booster?
Maybe it went bad? Stock LT1 master cylinder.

 

I've been considering the same C5 brake conversion you did and have been watching this post to hear the outcome. Have you figured out your brake problem? Thanks