jrfiero

On my 93 SC300 there are two cats, which the shop manual does not describe as having functions different from one another. I know on other cars, the front cat is a pre-cat (or light-off cat?), which really only functions for seconds or minutes after cold start, until the main cat gets hot enough to work. If you take the pre-cat off, for instance on my RX-7, the car still passes emissions when warm with just the main cat.

Any experience out there with removing the front cat, but still being able to pass emissions? I know it wouldn't pass the visual test, but my inspectors (VA) kinda wink at that as long as the numbers are good.

I ask because I'm wondering about headers, plumbed back into the main cat.

Do I understand correctly that the later 300s have two pre-cats?

rscott

there was an NA supra owner that did a smog test before and after he installed the XERD header. after the install he just barely squeaked by the reading with just a few points margin to failure. That header eliminated the first cat. I guess it all comes down to the health of the 2nd cat and of your motor in general.

DIrEctQL

You guys have higher standards than most states so I don't think we should have that much of a problem.

Around here when it's time for emission testing people generally replace the test pipe with a cat and drive around for atleast 20 minutes so the cat is warmed up.

Chris

rscott

actually i didnt take the state into consideration. I think he was in new jersey. I have no idea how strict their laws are. When i had the XERD header in and EGR blocked off i had a friend check my emissions. It was enough to label my car a gross polluter