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2 cat converters?

Posted: September 8th, 2007, 11:05 pm
by Dark_Rider2k3
so I found out we have 2 cat converters. This brings up a ?

If 1 of the cat converters was removed would I still pass my emissions test (PA if it matters..)

I'm just curious of this because i've never seen any car but ours that has 2 cats on it...

thanks!

Posted: September 8th, 2007, 11:53 pm
by shameem
Cars sold to california have two cats - one precat or warmup cat and one regular cat (because california has strict emission laws). Never heard of any other state adopting those laws - so you should be fine with removing the precat (not the regular cat).

Pre cat is the one right below the exhaust manifold. The regular cat is underneath the car right below the oil pan i think. After that there is the resonator and muffler.

Posted: September 9th, 2007, 12:13 am
by umcamara
I live in Canada, and I have a warm-up cat, as well as the main cat. My car, however, is a '96 and OBD-II.

Removing the warm-up cat will apparently not be an advantage to you. Yoda can explain it to you fully. But the just of it is that unless you replace the warm-up cat with a pipe that gradually increases in diameter at a certain rate, you will actually hurt your performance. Now the main cat, that's a different story.

You just want to avoid freeing up the exhaust too much, and decreasing the velocity of the exhaust gases.

Posted: September 9th, 2007, 1:03 am
by Mnemonic
one of my buddies gs actually has 2 cats i was helping him install his headers and looked underneath and saw 2 one in the usual stock right below the shifter and another one about 2' back

Posted: September 9th, 2007, 9:16 am
by umcamara
One of those would be the main cat, the other one, farther back is likely the resonator. I believe they all have one. It tries to cancel any resonant frequencies at the muffler.

Posted: September 9th, 2007, 9:38 am
by Mnemonic
no this wasnt a resonator, i know what they look like this was another cat

Posted: September 9th, 2007, 2:38 pm
by Dark_Rider2k3
as long as it's fine thats good to know..

I am buying repro's exhaust, and being new to this stuff, was afraid i couldn't pass emissions with his exhaust...