Effects of taking out my cat?

**Dave-TransAm** · 02-27-2011, 01:10 PM

What would the effects be of taking out my catalytic converter and putting a straight pipe where the cat was? I know its going to throw up the check engine light but what else will it do? Thanks for the help.

**pajeff02** · 02-27-2011, 02:03 PM

It will be louder.

**JayTA98** · 02-27-2011, 07:14 PM

wont the odor of fumes be stronger also?

**98maro** · 02-27-2011, 07:55 PM

Louder, more hp, gas smell all the time,
And it could run like shit if Is not tuned.

**Dave-TransAm** · 02-28-2011, 03:56 AM

What kind if tune would I need? And how much would it be?

**'02 WS6** · 02-28-2011, 04:18 AM

Custom tune......runs about $300-400.

**Spaz** · 02-28-2011, 06:59 AM

Originally Posted by Dave-TransAm

What kind if tune would I need? And how much would it be?

you'd just need the rear 02's tuned off... you could get 02 sims but they only last for so long...

**Dave-TransAm** · 02-28-2011, 09:56 AM

Originally Posted by Spaz

you'd just need the rear 02's tuned off... you could get 02 sims but they only last for so long...

How do I turn em off?

**35th-ANV-SS** · 02-28-2011, 10:08 AM

You get them tuned out or you get 02 simulators like mentioned already.

The first choice would be to get them tuned out.

And no, you DO NOT need a tune if you remove your cats.

**Spaz** · 02-28-2011, 10:13 AM

oh... you'll gain maybe 1 or 2 rwhp...

**'02 WS6** · 02-28-2011, 10:16 AM

Originally Posted by 35th-ANV-SS

You get them tuned out or you get 02 simulators like mentioned already.

The first choice would be to get them tuned out.

And no, you DO NOT need a tune if you remove your cats.

Eventually the computer will learn itself and no longer be fooled by the sims. General idea is if you have to use credits just to tune out rear 02s...might as well tune car.

**35th-ANV-SS** · 02-28-2011, 10:17 AM

Correct, but you do not have to get them tuned out if you are not bothered by the SES light or if you do not have to have emissions.

**Dave-TransAm** · 02-28-2011, 10:35 AM

So when I go to emissions in 2012 how long before then should I put the cat back on?

**'02 WS6** · 02-28-2011, 11:04 AM

You could always hollow the cats out or have an exhaust shop fab you a "test-pipe" that looks similar to the likes of a high flow cat. That's a popular alternative for those with visual inspections and no sniffer tests.

**Smittro** · 02-28-2011, 12:07 PM

Originally Posted by 35th-ANV-SS

You get them tuned out or you get 02 simulators like mentioned already.

The first choice would be to get them tuned out.

And no, you DO NOT need a tune if you remove your cats.

This....

**35th-ANV-SS** · 02-28-2011, 12:26 PM

Originally Posted by '02 WS6

You could always hollow the cats out or have an exhaust shop fab you a "test-pipe" that looks similar to the likes of a high flow cat. That's a popular alternative for those with visual inspections and no sniffer tests.

Most exhaust shops will NOT work on your car if your catalytic converters have been removed or if you have LT's which cause the cats to be moved from their original location.

Not having catalytic converters is illegal and an exhaust shop tampering which such a car or removing the cats can be heavily fined.

Not sure if this is a state law or federal as it deals with emissions. Guessing state law.

**'02 WS6** · 02-28-2011, 12:35 PM

Originally Posted by 35th-ANV-SS

Most exhaust shops will NOT work on your car if your catalytic converters have been removed or if you have LT's which cause the cats to be moved from their original location.

Not having catalytic converters is illegal and an exhaust shop tampering which such a car or removing the cats can be heavily fined.

Not sure if this is a state law or federal as it deals with emissions. Guessing state law.

For exhaust shops that do inspections I can see that, but there is also the excuse of "Doing this on my 'race car'' which doesn't need explanations to a shop. There are ways around everything...except in Cali maybe.

**Dave-TransAm** · 02-28-2011, 02:39 PM

Arizona does the whole test the exhaust deal so I would need to put the cat back on before emissions. I was just going to get it so I can bolt it right back on when I need to go. And im going to buy a used catalytic converter so i can have them hollow it out and run the pipe through it when I get the straight pipe put in in place of the cat

**pajeff02** · 02-28-2011, 02:41 PM

Originally Posted by 35th-ANV-SS

You get them tuned out or you get 02 simulators like mentioned already.

The first choice would be to get them tuned out.

And no, you DO NOT need a tune if you remove your cats.

Agree. Although the exhaust will be less restrictive, the combination of feedback from the front O2 senders and MAF will more than compensate for the change in airflow through the engine.