Well, it is finally time to update this thread. I have an HPDE coming up in a couple of weeks, so I had to buckle down and get around to making this happen.
Unfortunately, I discovered that, with the pieces I had on hand, I couldn't add this as a second cooler. So I went about swapping out the stock unit for this one. I took the measurements after the stock was out and found this Ebay unit to be the same width as stock, but 2 inches taller and 3/4 of an inch thicker. I think that latter number is probably the more important one as you are talking about a 60% increase over stock.
So with the lines and fittings that came with the kit, I had no problem reaching the passenger fender from the oil filter housing, and the adapter plate from bimmerworld was exactly the ticket for attaching to the housing. To make it fit, I only had to cut off one of the stock mounting bolts (the lower one). I then just bent up the tabs on the new cooler so I could bolt them directly to the "frame" of the car in front of the stock bracket. I was still able to use the stock hanger bracket to hold up the far side of the cooler.
I then trimmed the duct a bit, as well as the inner fender. I put the stock vent back on for now, but it is getting pushed out a little too much and my larger than stock tire is rubbing when at full left lock. I will find something flat at home depot to screw in there.
As for how well it works? Well, I don't think I'll really know until the track event. I figure, if needed, I could at least very easily add a second cooler now to this setup.
pics here:
http://www.flickr.com/photos/2930546...7633112382756/