for a great thread based on facts and lots of testing. This is what E90post is all about - enthusiasts helping each other get down the learning curve faster.
BTW, the only reason I found this is because a friend of mine with a Lotus Exige is doing the same and fabricating his own underbody aero kit and he was asking me some questions b/c of my engineering background. I told him that aero principles are basically guides, but that it's an empiracle science; so I did a search and viola. Just a note, but my friend is the reason I'm looking to get into tracking too.
How about an update, Brian? Depending on how my first track event goes, I may be interested in purchasing a kit from you in the next couple of months.
Keep up the great work