FYI, have an ER competition oil cooler for sale: http://www.e90post.com/forums/showthread.php?t=773556
I had to focus my efforts on an E36 M3 for track duty as it's a less expensive option once you get to a level of driving a non-race prepped N54 can't handle.
Don't get me wrong. I would love to make an N54 track-only car. I just can't afford to make a reliable one.