Weight is the primary enemy. E=MC2, or something like that, lol....mass has a much greater effect on braking than the horse power.
American Iron cars have run the Cobra brakes for many years - the overwhelming sentiment seems to be they stop as well as the Brembo 4 piston setup - only with less pedal feel/modulation and they go thru pads and rotors much faster.
The in between kits seem to be all the same in terms of rotor mass so they will likely not offer any more performance than the Cobras. You have to go to the big Wilwood kit or the Stoptech (on my wish list) with the 1.25" wide rotors to have more braking capacity.