No worries.
I came across a thread over on e90 post for the installation of NACA ducts on the under tray that I thought was brilliant. If you DIY the installation, you can do it for under $100 and if you still want to go to a BBK afterwards, you can. Here's the link to the thread
http://www.e90post.com/forums/showthread.php?t=1287364
It was my first time at The Glen, a buddy of mine owns
Apex Driving Events and I help him out.