The test day (Thursday, Nov 8) is conducted by the track. Last year it was $200 for the day and the amount was pro-rated based on how much of the day was left when you signed up - not sure what it'll be this year. I know we had a ton (as in 60) of cars in the "Big Bore" group last year with everything from ITA Miatas to 180 mph SPO cars. I plan to "encourage" the track to split that up differently in 2007.
There is no pre-registration for the test day - show up at the gate either Wednesday afternoon or Thursday and pay your money.
BK