The PO had the booster/MC mounted on the firewall but it was right over the engine. It was mounted that way because of the pedal location on the bracket. It was not right and was in the way over the motor like that so I removed it all and tossed it.

When I replaced it, I mounted it on the rib of the firewall and have no clearance issues. I prefer it on the firewall, no real reason, just a preference.

 

I run firewally masters for ease of maintenance and I like to keep the exhaust away from the brake system. The T bucket I am building will have it under the floor only because of lack of room, but that will have side pipes so no worries about the exhaust heat.

 

I vote for the under the floor model. The only problem was that I had to use a squeeze bottle with a angled end to add fluid occasionally. But, I really prefer the clean firewall. Jag