I run the 4 piston Wilwood setup on modified spindles. I went with it due to the ability to replace just 1 caliper if needbe ($150 from JEGS or Summit), and every brake pad company makes pads for the Wilwood Bridgebolt calipers. My track car has these, and I've been running them for 3 seasons. No regrets, they do very well on the track, pads are easy and cheap ($100-200/set depending on compound). I did have some modulation issues before I swapped out to a 94/95 Cobra MC and rear Cobra brakes. Once the MC was in, modulation is back and I have no issues outbraking lighter euro cars on track. Brake dust is something you'll have to deal with unless you go with a standard ceramic street type pad, but for aftermarket calipers they are not $30-50/set like OEM calipers. They do not eat up pads, but that's a compound choice. Mine, with race pads, outlast the OEM caliper race pads by at least 2 track weekends (I would eat through a set of pads in 3 weekends).
If you're looking to upgrade for looks, the 6 piston look cool under any wheel. You may as well bling out the rears with some matching calipers as well. Rotors you can go with a set of blanks, slotted, drilled, or go all out with a 2 piece rotor for even more street cred! As far as stopping power, can you lock up the brakes now, or get into ABS? If yes, then these won't do a whole lot for you unless you open track the car where heat management is necessary. I ran 99 11" front calipers with 98 rear GT calipers for many years on track and they did just fine with the right pads.
