Rear brakes- are the factory rotors slotted? >>
 

My discs are vented and slotted in the rear. (2001 225 Quattro Coupe)

I'm having the rear pads replaced tomorrow due to a rattle noise. I'm told that they're aftermarket pads (long story) and the dealer I purchased the car from will be replacing these with OE pads.

My reason for asking is that the car has an aftermarket sway bar and I'm wondering if these brakes aren't a performance upgrade as well. Thanks!

No, not slotted!!

You've got upgraded rotors. don't let them resurface them unless they're uneven
 

'cause they'll grind off your slots