[tock172]

I'm not a fan of Koni dampers, especially the Single Adjustable yellow ones that people seem to default to. In my experience, Bilstein sport dampers offer better, more compliant handling for street and track use, all while maintaining the ability to shrug off road imperfections with minimal motion transferred to the vehicle. Their mono-tube and gas-pressure design also lends itself to much better longevity that Koni dampers. Additionally, the Bilsteins are backed by a better warranty and are rebuildable if the time ever comes. I've had multiple sets of Koni dampers fail over short periods of use, and at least two individual shocks that were DOA.

As far as springs are concerned, my favorites are Eibach or Dinan, but I've heard zero complaints about the the BMW Performance Suspension springs. I've tried H&R and wasn't particularly impressed, but wouldn't consider them a dealbreaker. Just thought the Eibach springs gave a better ride.