Would I have done something differently?
Of course, there was a lot of trial & error in this so I could do another one in just 4-5 hours (minus the time it takes for the paint to dry). But other than that, I'm fairly satisfied with the outcome.
Perhaps I would have compromised the exit location a little bit, by going 4-5" lower and exiting through the bottom part of the undertray. But if you do that, the duct is now very close to the natural airflow under the car so I'm not sure how effective it would be. Decisions, decisions.
I'll report as soon as I can do a better test, and of course from my next track outing. Preliminary observations are that it works - for instance, the brake pinging after the car is stopped, due to the contraction as it cools off, is now mostly gone - which leads me to believe the brakes are now a little cooler.
2009 E90 M3 ED
2014 X1 28i ED
Last edited by adc; 07-02-2010 at 02:54 PM.