My 37 pickup has the master cylinder under the floor. I recently put in a completely new FatMan Fab Mustang II front end, new crossmember, all new disk brakes,everything front and rear. Replaced all the brake lines. We would have a pedal and then when turn the key on the pedal would go to the floor. So they checked all the lines for leaks, same with the calipers and such. Installed new residual valve. Installed new booster and new master cyclinder, I have brakes now but they are not very good. They will stop the vehicle but not in a hurry. The pedal also had about 2 inches cut from it before I purchased the vehicle and we relocated it for more throw but the brakes still arent that great. Any advice on how to get good brakes? I also wonder if i install a firewall mounted system if it would even fit with the steering and such being so tight now. Any help or suggestions is appreciated. Thanks.