So..... a while back a had a leak. Turned out to be the back drivers side bolt was snapped off as well as the front drivers side and one of the middle passenger side bolts. Was only hearing any sort of leak from the back drivers side so I got one of the dorman fix clamp things and with some cursing managed to get the thing installed and fixed the leak. Now a bit over a month later I started hearing a new blow. So on looking under the hood I was figuring either it came loose or another one was going to need to be clamped.

Well damn. The passenger side manifold itself is cracked and seems to be getting louder by the day. So on thinking about this for a bit and knowing how often this problem comes up with not just us but others with LS engines too I said to hell with it. After reading a couple of other threads on this I decided to go ahead and get the full OBX long tube header kit. Also went ahead and ordered a set of bolts, a new dipstick tube, a set of top notch gaskets, a couple of O2 sensor bung plugs, and a set of spark plug wire heat sleeves. For me anyways - the rest of today I also have a bonus cash back deal with the eBay bucks program to get 8% back which is nice. So in a couple of months I'll have an extra $60 to blow on something.

I went ahead and ordered most of what I did based on others reviews of doing this very same project. The OBX LT headers have a couple of extra O2 sensor bungs which we do not use so that is why the two extra plugs. I've read of other saying that while overall the OBX setup is, for the price, an excellent deal that they are not always perfectly flat and the included header gaskets might leave a bit to be desired. I've used Remflex gaskets before and they are awesome - a full 1/8" thick with 50% crush and they also eliminate the need to re-torque your bolts. I went ahead and ordered the dipstick tube because I've seen many report that the original collects water around the base and there is a chance it might be rusted through and break off. New tube only added $16 and worth the piece of mind knowing that I will not need it. If I did not order it, mine will most certainly break off and then I'd not have it, logic states that since I've ordered it mine will be fine.

Anyways - found all of it on eBay. Ended up right about $822 with everything including shipping and after the bucks bonus I'll get about $60 back. Anyways - now I'm going to head outside and pull my truck out and drive it for a bit. Going to start soaking the manifold bolts daily with Kroil now. I'm just hoping the three that are snapped off have some still sticking out to make removing them slightly less painful. All in all - based on this thread H2 OBX Long Tube Header w/ High Flow Cat Install With Pictures - Hummer Forums by Elcova
I'm hoping I have everything covered and can knock this out myself in a single day. Short of the broken off bolts giving me grief it should not be too bad. Of course now I'll be itching to get Lew to do me up a custom tune now too (I already have an Intune) to really take advantage of the greatly improved exhaust (also already changed out the stock muffler for a Flowmaster big block series which sounds great by itself).

I'll update with some pics and all after everything gets here and I get to work on it.

 

Good luck with the install. You'll like the long tubes... you'll be itching to get a remap on it

 

From everything I'm seeing I should be able to bolt the kit on myself in half a day. That is of course barring any issues with the 3 broken bolts and potentially any others that might snap off when I attempt to remove them. I do have the right tools here though - 10 ton floor jack and jack stands will make quick work of getting her up in the air. I've already soaked all the bolts once with Kroil and will keep soaking them a couple of times a day until next weekend when I plan on tackling this.

Plan is to get the truck up on the jack stands, pull the front wheels, and pull the wheel house liners, and remove the skid plate and cross member underneath for the majority of the access I should need. Just prior to trying to trying to remove the remaining manifold bolts I'll start it up and let it warm up a small bit which should also help with those. Mine is an 03 so I'm sure they are going to fight me. I do have a mig handy so if it comes down to it I can try and weld onto the broken bolts to give something to grip them but I'm hoping they will come out nicely.

From everything I've read the rest should be pretty easy and the new stuff should bolt right on. The one I'm unsure of is if the pipes I ordered will have the EGR mount on them. If they do I'll be cutting that off and welding the hole up as I'd rather not have it sticking out and making a block off plate for it..

 

What about cats ? From the above i think that's pretty much what the garage did when they did mine, although i dont recall EGR. They definitely removed the cross member. I also opted to have the sump gasket changed at the same time as there was a small leak, and well it just made sense. I went the dynatech route, so bought the fast cats with it. I didn't have any issues with spacing or anything with mine. I was worried the plug leads might be close to the pipes, but knock on wood, no issue so far (I had it done a year or so already).

https://www.hummerforums.com/forum/h...catback-36194/

(in case it helps with reference photos)

 

It's going to sound great. I did some shorty headers on an H2 once and even those sounded much better. Kroil is the best. I use it in my shop. Look forward to seeing your install pictures and test drive report.

 

Yep - looking forward to it. Baldfox - the set I'm getting includes high flow cats and all.

This is a link to the actual set.... OBX Performance Exhaust Header 99-05 GM Hummer H2 GMC Denali Silverado 6.0L

On the 2003 (and I think through 2005) are also true duals all the way to after the muffler. Oddly after the muffler they Y into a single exit pipe. I've already replaced the muffler itself with a Flowmaster Big Block 50 series muffler which by itself made it sound a ton better.

The one thing I'm wondering is if I would further benefit from a crossover pipe somewhere in the exhaust which it does not have.

 

Thats a good price for that set up!

https://www.carid.com/articles/are-x...t-systems.html

Maybe this will help on the rest..

 

Shiny, purty stuff!

I'm wagering that tomorrow is going to be a long day...

 

Gettin' started.... and a before shot of the passenger side manifold.

 

Its done! Sounds badass too.... now it sounds like an old hot rod! Not 100% sure on whether it will be too loud for my tastes yet but in a 10 minute test ride (with it floored half the time) I'm digging it. Out of 4 broken bolts - 3 were broken off flush and 3 extracted perfectly fine. The back driver side one kicked my *** for 4 solid hours before I threw in the towel. Drilled it perfect (using a smallish right angle drill) tapped the extractor into it and started going at it very gently and slow like the other and "plink"!!! the extractor snapped off in it. This bolt was one of those that broke off flush, actually about 1/16" below the surface, the extractor snapped off with about 1/8" above. Tried grabbing at it with multiple pliers and vice grips and just could not get ahold of it. Cut a slot in it with a dremel and tried turning and of course half of what was left just snapped off. then wore out a couple of drill bits trying in vain to drill some on the hardened steel extractor. Finally used the dremel and get it flush with the head and gave up. Fortunately I still had the broken bolt clamp that I had been using before and was still perfectly fine. So I bolted that back onto the back side of the head and used it to clamp that one back end of the new header which seems to have worked just fine. I'm a bit annoyed that I failed on that one when I was able to get the other three out but oh well.

Couple more pics.... Also went over the front brakes while I was in there with new drilled/slotted rotors and ceramic pads.

And..... I now know I pretty much need to rebuild the entire front suspension. I sort of expected that though. Couple more pics - one side cleaned up, then with the new header on, and a shot of the new brakes.