the only thing that matters is the direction of the internal vanes---- if they are directional. If the vanes are straight (like a wagon wheel) the rotors can be mounted in either direction.

The info I read from zeckhausenracing.com (very reputable brake specialists) contradicts the advice given so far in this thread-----
for rotors with internal directional vanes, those internal vanes should LEAN TO THE BACK of the car on each side,
eg. for the left side, the top of the internal rotor vanes should tip to the right (the back of the car).

The idea of these vanes is to EXTRACT hot air from inside the rotors, not to scoop cold air into the rotors.
Cold air gets directed to flow over the rotors, and the vanes suck out the hot air.

To read more details, go to the zeckhausenracing.com website, and look under their Technical menu:
Which way? How to properly install plain, slotted or drilled rotors

Lots of good brake info on that site.

 

Thanks all, i called stoptech and they told me that the brakes are installed properly. Sounds to me like they need to be re-bedded. They also recomended that i buy new pads and gave me a part number for them. They were super helpful. They also said that if it didn't work then to call them and they'd work something out with me on new rotors.

First i'll try re-bedding them then i'll try new pads.

 

Silly question does installing aftermarket rotor void any type of warranty I have with BMW? I'm always sketchy about doing any type of upgrades fearing they'll look for any reason to cut off my warranty

 

I believe they just wouldnt cover anything to do with the brakes if you do go with aftermarket rotors and pads or even BBK.

 

boo to that.