Beginning in 2009 aftermarket CAT sales in California will be more
restrictive due to tighter guidelines.

If you live in California, you may want to buy a replacement CAT before the end of 2008 if you think you'll be needing one at some point in the future.

If vendors have to sell CATS with guaranteed 5 year life and BAR certifications they will no doubt be more expensive.

http://www.bar.ca.gov/80_BARResources/ftp/pdfdocs/ARSC-summer08.pdf