I have a 2006 H2. Back in Nov./Dec. of 2015 I had to replace BOTH of my catalytic converters. In the last 3-4 months my H2 has set a couple of codes for a cylinder misfire and converter failure. After taking it to the mechanic and having them replace plugs, wires and doing some maintenance to check on other things that could cause this they recommended I take my H2 to a muffler shop. I have made my appointment to do so. My question in regards to all this is that I have been considering replacing/upgrading my exhaust system completely. Has anyone done this and if so do you have any recommendations for me? I have looked into options like Magnaflow and Borla. Not looking to make this thing a fast and furious racing machine but wouldn't mind a little more power or fuel efficiency. Any thoughts on this would be great. Thanks!

 

As I have gone through my H2 I have replaced both cats, exhaust manifolds with headers, plugs wires, knock sensors, etc. I also removed, cleaned, and tested all of my fuel injectors. If you happen to have a leaking fuel injector, this can lead to an early failure in your catalytic converter. You may want to check those out. As far as exhaust goes, I put stainless headers, magnaflow stainless cats and will be installing Borla from the cats back. I like the sound without the drone inside the cab.

Good Luck!

 

Similar to what I've done. I bought the OBX full stainless long tube headers and high flow cats kit then got a full stainless Borla (GM Performance Parts OEM made by Borla) cat-back kit. The setup really sounds sweet and has no drone. I got the "touring" cat back kit which is not quite as loud though. The headers do have the distinctly metallic sound. As a whole, the full system did give a nice boost in overall performance.

 

Where did you pick up the OBX LTs? They used to be posted all over the place but now there's literally one seller on ebay charging upwards of 1k for them.

 

There are still plenty on eBay with them.... or just search on there for Hummer H2 Headers and there are some others too. This one is the OBX for 03-06 models.

https://www.ebay.com/itm/162521207399

Now finding the original GM Performance Parts stainless cat back sets.... not nearly as easy to find. Those were made by Borla for GM though. Borla did have some of the sets on their closeout corner for quite a long time. They do still have some of the nice tips though...

https://www.borla.com/products/closeout_corner.html

Could also get one of the GM truck exhausts and modify it as well. Just not going to be an exact bolt on fit.

Another thing to be aware of is there are two different versions of the stock exhaust on the earlier models and the 08/09 models have a third version. Have to look underneath to be sure you get the right setup.

 

That's a hell of a lot better price than what was showing in my H2 feed. I might have to pull the trigger on those. Itching for a project for my rig lol. I think I've put enough lights on the thing.....

 

Kit was pretty easy to install. I did get much better quality gaskets and new header bolts. I also went ahead and replaced both of the downsteam O2 sensors for good measure.

Toughest part for me was 4 broken header bolts and I was only able to extract 3 of them. The driver side rear bolt I just could not extract. I had one of the dorman clamp brackets on to keep the stock manifold from leaking so I reinstalled that bracket in the one spot. The other 3 I was able to extract.

What I did - I soaked all the bolts (on the manifolds and pipes below) a few times over the week prior with Kroil (stunk a bit once warmed up but not terrible) then right before removal and then ran the engine for a few minutes to warm things up just a little. I put the front end up on jack stands and took the front wheels off. Then removed the fender flares and wheel tub linings to make things easier to get at. Only takes a few extra minutes and well worth the easier access.

These are the bolts I bought https://www.ebay.com/itm/272637931303
Cheap and well worth it. This is the gaskets I bought - best you can get. https://www.ebay.com/itm/262988751203 - Remflex #2008. The gaskets that come with the headers are rubbish...

Here is where I posted on here about when I put them on and all with a few pics.

https://www.hummerforums.com/forum/h...g-tubes-38364/