A while back I had a short shifter adapter installed and had to leave off the shifter box cover which the heat shielding covers up. I'm guessing heat from the exhaust and I'm in long durations of traffic my shifter boot and console are getting pretty damn hot. Has anyone else experienced this?

 

It gets warm down there. around the boot and sometimes on the console, Make sure that when the heat shield was put back it was put back correctly.

 

The heat shields in the Mini is the most under-appreciate parts. When they do their job no one appreciate it. If you think the shift boot area is warm driving on the road, you ain't see nothing yet.

When driving on the track, I get 8.9 miles a gallon, and the exhaust has no hint of unburnt hydrocarbon. What does this mean?

According to the law of conservation of energy, those excess petrol that does not make power has to go somewhere. The combustion of the unburnt fuel happens in the catalytic converter. Everything downstream of the cat gets super hot. So hot that the exhaust pipe clamp grew red hot and stretches.