The pre-cat has been known to fail and either collapse on itself or crumble and clog the main catalytic convertor further down the exhaust system.  As a purely preventative procedure, we inspect ALL pre-cats to make sure they are intact.  If the pre-cat is failing, you can punch out the rest of the pieces with a piece of pipe or equivalent.  If you find the pre-cat in pieces, we highly recommend to inspect the main cat for clogging!  The pre-cat was designed by Mazda to clean up emission, especially at cold-start.  J-spec FC's do not come with pre-cats, and in fact come with a downpipe - stock.

If your FC is down on power, and water temps are abnormally high, check the cats to see if they are failing.

Questions?  Comments?  Send mail to: