i have the 4 pot calipers on my car.( mazda calipers and vented disk ). they work well.i have a extra set of 4 pot calipers. thinking about putting them on the rear...brake balance..hum, that the problem... my thought.. lets say the stock front brake pad is 48sq. cm. and the rears are 75% of that...i am thinking about putting the 4 pots on the rear..and trimming the friction part of the pad to 75% of org. sizr. leaving the metal plate the same size... is this a workable idea?