Originally Posted by andrey_gta
Look at Ebay for 135i brakes or calipers. Used will save you money, I've seen grey 135i take off parts for less than 1.5k. The performance pads I believe share the same number as stock 135i pads. The rotors are the only difference.
I would also call local dealerships and ask if they "upgraded/updated" any of their lot 135i cars to BMP brakes, they might have the gently used stock 135i brakes.
Also, understand that the kit will add weight to the car, and many 128i guys think its just bling since the 135i brakes have let people down on the track(the pistons & dustboots crumbled under extreme heat, needing rebuilds using better parts).
I don't track my car but other shop people told me the same story that extreme heat will destroy the rubber seals on the caliber.