David,
IT stands for Improved Touring. They are Regional only classes in the SCCA and can't participate in the National Championship Runoffs. But, they do have similar end of year event at Road Atlanta for the Regional only classes.
IT is in the GCS - article 17.1.4
http://www.scca.com/_FileLibrary/Fil...vedTouring.pdf
ITE is a class for cars that don't have an SCCA class. The rules read something along the lines of any car is eligible that is eligible in another racing series (such as NASA or SCCA World Challenge). So you get a pretty wide spread of cars in the ITE class, and very few entries. In my division the last two years, ITE was won by an ex-SCCA World Challenge C5 Z06 running north of 500 HP, with wings, etc. Very sweet and fast car, but not cheap.
