I have a 03 MM and It came Equiped with the Clutch alternator pulley which requires a special tool to remove, I Left the pulley on and just installed the crank and water pump pulleys. I did Notice a big difference in performance!
and I also noticed a big drop in voltage also.
At a idle, Rolling up a window with the headlights on put the voltmeter at 10volts, At a trafficlight the volts sit at about 12 and it even caused a noticable rough idle due to lower voltage to the injectors. However, Driving the Car put the volts at a normal 14 and I never had a problem starting the car or running accessories with the engine off. I bought the Car used so my Alternator may not be putting out the Voltage like it should and It may be only me with this issue lol but thats my experience with the Pulleys installed