They are the only ones. This has been debunked several times and we have shipped roughly 20 of these kits with no issues. Rear bias was caused by way too much rear pad. We had a brake engineer (Not a disgruntled X-Ford one) run the analysis which accounts for CG, wheel base, tire grip, all caliper and M/C bore sizes and the results were opposite, meaning the claimed improvement should have been worse. Bad data can be manipulated into any story you want. The PP M/C uses a slightly larger bore but is combined with a specific booster to offset the additional pedal effort. Using the slightly smaller bore M/C (which is the same one used on the GT350 with its many more caliper pistons and area) from the base cars with the 6 Piston Brembo's hydraulically is more than sufficient. The 6 Piston Brembos installed on the Base Brake S550's actually reduce the total piston area by 4.7%, not increase it as has been suggested (again, bad data) which in the real world amounts to nothing. The Base M/C will have zero issues supplying volume to push on less surface area. That is very basic math. Ford would include a M/C and Booster with the kit if it was needed.Read Vorschlag's posts, the master and booster are different. Only installing the calipers and rotors actually REDUCES stopping efficacy by too much rear bias IIRC. They got slower and had bad pedal feel without the additional parts.