My voltage had dropped to the low 12s at idle. Read that a 150 amp (vs the 120 in the zhp) from an '05 325i fits perfectly if you have the oval connector. They're around $120 at autozone too, so significantly less.
Popped it in this afternoon and it's doing just dandy! Back up to just under 14v.
Part number 1108
http://www.autozone.com/external-eng...8_100967_3001/
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