Cutting out the Cat

SimLyons · Post by **SimLyons** » 21 Dec 2011, 19:35

If I remove the catalytic from my exhaust, what happens? Not talking about the legal ramifications. I mean the 02 sensors, Codes popping up, etc. I have read in MVS someplace that just leaving them in is needed, but maybe relocating them back a bit? I don't really know what will happen but I want it off.

Another question: Will it cause any problems with the valves (exhaust) or anything else?

Thanks for any help!

Post by **Fish stick88** » 21 Dec 2011, 19:38

why do you want it off? it will indefinately throw O2 codes as well as the possiblity of making your car go haywire because they're not there, (as far as rich/lean) goes.

whoa · Post by **whoa** » 21 Dec 2011, 20:05

And the legal rules are there for a reason. You will be feeding your community's children that poison. Be a good scout and play fair.

SimLyons · Post by **SimLyons** » 21 Dec 2011, 22:10

Well, yes...maybe. I live 10 miles from town and there are no kids within 5 miles. Why I want to do it? They plug up.Increase back pressure. Cost a lot to replace. And I drive this particular car about 400 miles a month, MAX. More like one tank of gas. What I add to the mix out here on the high desert is nothing compared to any intersection where there is more than one car idling.

Srini850 · Post by **Srini850** » 21 Dec 2011, 23:49

One option would be to throw a high flow cat in there. Still get the performance and can stay legal.

As far as taking it out completely, you could put an O2 spacer or make one to put on the rear O2 sensor (Don't do this for the front sensor).

I haven't heard of engine problems from cat deletes, it's more that your car just smells worse and is louder. Your front O2 affects most if not all fuel/air metering while the rear O2 just makes sure the Cat works, hence the reason you back it out of the exhaust.

Seriously, though, the benefit of running with no cat is marginal compared to a high flow.

SimLyons · Post by **SimLyons** » 22 Dec 2011, 11:54

Hi-flow sounds very interesting. Any suggestions for sources? I appreciate the reply! Thanks!!

Post by **JDS60R** » 22 Dec 2011, 12:07

www.magnaflow.com

weld ins are very cheap and the sensors love these cats.

Post by **JDS60R** » 22 Dec 2011, 12:20

It would be a great time to take a larger stainless catless downpipe and have a magnaflow welded in. Or if you have a local exhaust shop who will build with stainless and do it cheaper - even better.

Srini850 · Post by **Srini850** » 22 Dec 2011, 13:38

JDS60R wrote:It would be a great time to take a larger stainless catless downpipe and have a magnaflow welded in. Or if you have a local exhaust shop who will build with stainless and do it cheaper - even better.

+1

I'm kind of in the same boat right now. Preparing for a manual swap and will probably change out the exhaust while everything is apart. Got the dreaded p0420 code that I've been resetting every few hundred miles.

You could also get an Obx exhaust, which comes with no cat and weld a high flow in there. Just with a change in exhaust and a high flow, your car will breathe new life.