I remember someone posting an Autox video early on showing a lot of chassis flex around the door frame (was that you @
feldy?). This will limit that, however, I don't know how effective it will be in your lap time.
Here's a video I looked up. Skip ahead to 134. It's a little harder to notice on a black car, but you can see the door flex in and out on each turn.
[ame="http://www.youtube.com/watch?v=UNc5ABlY3o0"]FRS Miller Park Autocross Run #4 - YouTube[/ame]
Here's a better one. Skip to 1:20.
[ame="http://www.youtube.com/watch?v=l3i_RVz8F1Y"]FRS First Drive with Jeff - YouTube[/ame]