Ben,
13" is 330mm which is stock, no? And the Brembos are also OEM? If so, the factory 36mm rear piston size is way too small and as you have found, the fronts lock first and often.
Enlarging the rear piston size from 36mm to 38mm duplicates the brake clamping balance of the StopTech front-only caliper kit. They decrease the size of the front pistons relative to the Brembo 4 piston caliper; mathematically the same balance by achieved with the stock front calipers and increasing the rear calipers to 38mm.
The 40mm version obviously goes another step towards more rear brake and in everyone's experience, provides a brake balance that feels like all four corners are finally each doing their fair share. You will also be more comfortable with pedal pressure, i.e. no more surprise that you pushed too hard and suddenly one wheel isn't rolling anymore. I can send you a few references of folks on this board that have them.
It's a modified version of the OEM caliper, so it's indistiguishable by external inspection, even with caliper removed. You can use it with any compatible Viper rear rotor, retain the OEM brake pad size and brake line fittings. It mounts with factory hardware in original location, so no cutting off any arms. Do I sound like a commercial?
Let me hijack my own thread and ask if anyone has OEM rear calipers for sale. Getting cores to work on is the big bottleneck - PM or email me with what you have and how much you want for them. Thanks.
