The Dinan underdrive pulley is made of aircraft quality 6061 alloy, is anodized black and does not modify your harmonic damper as some underdrive pulley kits do which can be harmful to your engine.
This product is backed by our industry leading 4 year/50,000 mile warranty so you can rest assured that you are purchasing the best quality product for your BMW.
+11 horsepower @ 8400 rpm and +7 lb-ft torque @ 8400 rpm on a stock car.
NOTE: BMW changed the belt configuration from a single-sided power steering and AC belt to a double-sided belt for M3's that were produced after May 2008. Please check with your dealer to find the correct Dinan part number below.
D560-0003 for 2008-5/08 production date with single-sided power steering & AC belt
D560-0004 for 6/08-2013 production date with double-sided power steering & AC belt