Headers without deleting cat

**TheFragrantVagrant** · 04-28-2013

Is there a header set up that doesn't remove the catalytic converter?

Headers are almost universally recommended over the powerlog + downpipe combo for someone who plans to mod substantially. That said, I live in a state that has emissions testing, and need this car to be legal (it's a daily driver as well). Here are my questions:

1. Is there a header set up that, without any modification, doesn't remove the cat?

2. Is it possible to combine a header with a different downpipe to avoid removing the cat, and is this something I could do myself, without welding?

I assume if neither of these are possible, I'd have to take the car to a shop to get the headers installed with a cat. I have a 2002 gtp if that makes a difference.

Thanks!

**CTKGP09** · 04-28-2013

1. companies like ZZP may offer an option to add a cat with their headers, but usually when we buy headers and need a cat, we buy the magnaflow high flow 3inch cat
2. any set of headers can be cut and modded, just need sum skillz

**dbextreme** · 04-28-2013

The Speed Daddy's I got have a space in the down pipe to either put in your cat (typically the Mangaflow 3" like CTK said) or the supplied ~12" section of 3" pipe with two band clamps.

**coolone** · 04-28-2013

I got my 3" down pipe with hi flow cat from ZZP...
I installed Ceramic coated Pacesetter headers.
: )

**Kilroy** · 04-28-2013

Will the high flow cat not mess with the second O2 sensor readings and throw a code?

**coolone** · 04-28-2013

Nope... No codes, everything installed and worked nicely.

I may take the cat out eventually, but for now it's in and stays.

**khornocker** · 02-26-2016

id like to bump this old thread if I may.

I'm getting ready to install speed daddy headers on my 2005 GTP. My state does not require emissions testing so im thinking about not installing a catalytic converter back on my car. what kind of CEL am I going to see after my header install? and how can I get the future CEL to go away?

also, what are the pros and cons when deleting the cats.

**J57ltr** · 02-26-2016

For 05 your going to have a hard time with the cat test that happens. But using a tuner you can set the codes to not report. I am about to install SD headers and a 3" Cat on my car, we'll see how it works.

Jeff

**Scottydoggs** · 02-26-2016

i was just looking at 04 and 05 bins in tiny tuner, i see no cat test listed.

your best to get a cat. they fit in place of the mid pipe in the down pipe of sd headers just fine. i got a 3 inch hi flow, your conna want something closer to stock cell count to keep the pcm happy.

ive seen a guy here, he cut off and opened up the in and lets of the stock cat and welded the 3 inch pipes to it. iirc hes in ca and needed the factory cat.

in your case its likely the best route to go due to the pcm using the rear o2 sensor.

**Fivefingerdeathpunch** · 02-26-2016

I wouldn't doubt it if the cat test is there but you can't turn it off.

My 06 sierra had a cat test that could not be disabled if you left the rear o2 sensor's unplugged, but if you kept them plugged in and turned off the error codes it was all gravy. Just a weird thing with those pcm's.

**khornocker** · 02-26-2016

Do you think this cat would work.

MagnaFlow® 54959 - Federal Catalytic Converter (3" Center Inlet / 3" Center Outlet more details on - http://www.carid.com/magnaflow/catal...FdgNgQodxfoIww

**REDCRAPGP** · 02-26-2016

I think that's the one I run but my cat codes are deleted..

**khornocker** · 02-28-2016

Originally Posted by J57ltr

For 05 your going to have a hard time with the cat test that happens. But using a tuner you can set the codes to not report. I am about to install SD headers and a 3" Cat on my car, we'll see how it works.

Jeff

What brand cat are you installing