We also sell the BAER brake kit's too and right now we are offering a 10% discount on them so you would most likely save that added $600!
BAER does also have the 6 piston / 6 piston set ups for the Regal and they also came out with their own BAER brake master cylinder now which will be available after the new year...
The bore size depends on what braking system you have and what the manufacture recommends for their set up... If you buy brakes from us we will set you up with the Proper brakes for your brake system.. BAER's new "Remaster" master cylinder comes available in many different bore sizes to fit all the different brake systems used on our Regal's today... (Vacuum, Hydroboost, Powermaster)