[TR] cleaning the GT6 exhaust

[Randall]

> This year I'd like to get its idle exhaust cleaner.

In what way ?  Less HC, CO, CO2 or NOx ?  

They are more-or-less contradictory goals, so it's important to know which
one we're trying to change, IMO.

As a very rough rule of thumb, high HC is usually ignition problems, while
high CO is usually a mixture problem.  But things like funky valve
adjustment or timing can cause both of them.

Little details like what emissions equipment it has might be helpful too ...

Randall