Originally Posted by RagingKileak
I can say this.... When I took my E92 to the Ring (running Marcel's old drilled and vented disks, with new cool carbon pads and standard calipers) the brakes were cooked within the first half of the lap.
That said, there is a big difference between 'a few track days' and 'the Nurburgring.' We might all go straight from nothing to Nurburgring, but that doesn't mean we should be. It might be that my setup is perfectly adequate for Croft, or Knockhill. I basically agree with Phil, in that actually for day to day motoring my setup is more than adequate.
It's worth noting that when we went to the 'Ring, the ambient temperature was 38 degrees, so the cars were struggling to cool everything really and IAT's were high.
Always happens to newBs as they don't brake properly.
I could always do two consecutive laps on the 'Ring with these brakes, and Tony also drove them (to compare them to his APs with track pads) and said they're not too bad. The 'Ring is actually not too hard on brakes as there are lots of stretches where you don't need to brake much (if you know the circuit) and where the brakes can cool down. On the GP circuit or Hockenheim for example that is much worse, and with the stock setup you'll always have braking problems there.
Still, if you seriously track your car you'll always want a BBK. But the good ones are never
cheap as fabrication and R&D are expensive. Before going with the Performance Friction BBK that I have now I also did some research - the AP kit is the least expensive one on the market, and you only need the front set really. Combine it with (better) PFC discs and you have an excellent setup that will not disappoint you.
Other (but more expensive) alternatives are Brembo (355mm, the 380mm is too large for most wheels), StopTech (which is what Alpina uses on their B3 GT3 model) or Performance Friction. A friend of mine has the Brembo set and it's excellent, and for myself I'm more than happy with the PFC set. I don't know anyone personally who runs the StopTech BBK but considering Alpina uses it and sport auto in their supertest were positive about it I wouldn't hesitate with it either (although the PFC kit is IMO the technically most advanced one of all three with the monobloc design and the 4 pads per caliper).
I personally know someone who bought the K-Sport kit and was very disappointed with it. Lots of noise and vibration and the braking performance was worse than with the stock ones. He threw them out in the end and went with Brembo.
The BMW Performance is not a good idea on the 335d either as it is designed for lighter cars and uses smaller discs than the stock setup (338mm instead of 348 IIRC). Tony tried it out and they were shot within one afternoon at the 'Ring.
Personally I would only consider a BBK if you really want to track your car regularly. It only makes sense if you go with a good set, and these are quite expensive.
Just my 2c, hopes it helps your decision process.