I5 Catalytic Converters

[rascole]

Who has replaced the front and rear catalytic converters? What have you used? My exhaust just started to rattle and throwing a O2 code. With some advice I'm certain it is the rear. Not concerned with California compliant, will be registered in Texas soon.

 

[Happy Hummer]

The front headers have the cats upstream as part of them. The rear cat is I believe pretty much stand alone and you can replace it as such. There a number of options.

hummer h3 catalytic converter - Google Search

 

[alrock]

Someone removed my second cat in my 07 but it's not an issue for me since the 2nd cat is not monitored in 07s like it is in 06. So one solution might be to cut out the 2nd cat and relocate the rear O2 sensor and move it upstream. With that second cat out, I'm pretty sure I gained about 100 hp and 100 ft/lbs. Or maybe that was the stickers I added.

 

[crwalkerasla]

My rear CAT was removed from my 06 prior to my purchase also. ran fin with idiot light on. PCM of NC said that they could turn it off with the tune.

 

[rascole]

I bought a replacement rear section including a cat from Amazon, I thought about just a cat replacement but the pipe has been abused over the years and for a cat and new pipe custom made was over $400, $250 on amazon was a steal.
Alrock, if you can send me the link for the stickers, I'm looking for cheap power.

 

[Jeepwalker]

There are a number of relatively inexpensive aftermarket H3 J-pipe's with Cats listed on Ebay. Or at least there used to be.

I haven't tried them and can't say from personal experience, but there've been a few on the forum over the years who have. Good luck!

 

[rascole]

Got the new rear cat, Walker Ultra EPA 54480. By comparison, the pipe alone should gain me 100hp. The stock 2.5" pipe is horribly pinched. For a few more $$$$ I'm sure a good shop could make a free flowing pipe. But, I need quick an simple.

 

[Jeepwalker]

Great info. How much was it? Let us know how it goes....

 

[rascole]

Great info. How much was it? Let us know how it goes....

$250 on amazon open box deal. Will install this weekend and see how it works.

 

[alrock]

Got the new rear cat, Walker Ultra EPA 54480. By comparison, the pipe alone should gain me 100hp. The stock 2.5" pipe is horribly pinched. For a few more $$$$ I'm sure a good shop could make a free flowing pipe. But, I need quick an simple.

Make sure to install the manufacturer's stickers in that box to unlock the full HP potential.

 

[Ridinhigh1500]

I ditched my exhaust manifold and ordered one through www.jagsthatrun.com

 

[zebra]

shoot - i didn't think nobody still had a LT header for these. every time i'd looked for one, everybody was out of stock.
this colorado one fit right?

 

[650Hawk]

Wow, crappy looking weld on the Walker O2 bung.

 

[Ridinhigh1500]

shoot - i didn't think nobody still had a LT header for these. every time i'd looked for one, everybody was out of stock.
this colorado one fit right?

They are basically made to order from the place in California and the fitment is excellent. Since putting it on the throttle response is amazing and it sounds awesome too.