Try this link for SCCA Solo II regs [ http://www.scca.org/Solo/Index.asp?IdS=00A02B-7728400&x=050 ]|070&~=. If all you have done is add a cat back, I think your NA will be in F Stock. The following is based on 2004 rules. Don't change to a cone filter unless you want to move to Street Prepared, although K&N replacements for stock filters are Ok in Stock classes. Prep your car at home the day before. Remove anything from the interior that can move around freely. Think about how you want to mark your number on your car - shoe polish???Arrive early. Walk the course several times. Allow time for your tires to cool from the trip to the site, then adjust pressures upwards. If your region does not require you to work the event, volunteer to as a "cone picker" anyway. You will learn a lot by watching and talking with others who are doing the same thing. Don't hesitate to ask questions, but not of the people doing timing. Enjoy!