A tale of two keys: Boss 302 TracKey unlocks track-ready performance

But for drivers who want just a little more out of their Boss 302, Ford will supply owners with a special TracKey, which automatically tells the powertrain control module – PCM – that the driver wants to experience a competition-ready track experience. The key engages a software upgrade called TracMode on the Boss 302′s PCM that alters more than 200 engine management paramenters, most notably an increase in low-end torque.

via leftlanenews.com

I am not a huge Mustang fan, but this seems pretty cool. although I am not sure why I would ever use the "not-awesome" key.