My bet it on the unlatched trunk theory, the tailgaters didn't shut the lid properly after grabbing a pizza slice from the trunk
I have spun my Boxster a dozen times or more and never seen any kind of flexing that could open the trunk.
Glad to hear you did not hit anything.
However, if you had taken a Porsche Performance driving school, you would not have spun out. I think you have been given a sign that you should do that so you can avoid the numerous road obstacles in Texas
Just Sayin...!
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"It broke because it wants to be Upgraded

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2012 Porsche Performance Driving School - SanDiego region
2001 Boxster S, Top Speed muffler, (Fred's) Mini Morimotto Projectors, Tarret UDP,
Short Shifter, Touch Screen Dual Din Radio, 03 4 Bow glass Top (DD & Auto-X since May 17,2012)