the ones that came on the car...Bosch probably....believe me...I wouldn't start messing with that stuff....I have tried on BMWs and Benzes and screw it....the best stuff is what comes as original equipment. Why wouldn't BMW or Mercedes or Porsche or Audi or any of them not put the very best quality components that can be had? Why can they command the purchase price they can, why do the cars, in fact, last so long properly maintained? my position is, and has been for 15 years, is keep these boys exactly stock. bmws and mercedes will be incredibly reliable cars if you keep them maintained to spec....i gotta go now, as i am in illinois i have to watch blagovich on letterman ...this should be fresh....