Just wondering....I took my E to the track at Putnam, IN and absolutely TOASTED the stock rear pads by the end of the first day. The fronts are absolutely amazing though! Those 15 in rotors with 6 piston calipers are deadly...I never thought I would be able to keep up with the Porsche's in braking power but I actually out-broke many of them. I put some replacement performance pads on the rear for the second day, but I was wondering if there were any performance pads and calipers that I could put on that were bigger...I was thinking that those 14s would go pretty nice if they could fit :)
Contact Porterfield Enterprises in Costa Mesa, Ca. and explain to them your situation with the rear brakes. They will be more than happy to help you. They build most of their pads in house. Here is the link to their website. http://porterfield-brakes.com/index.php