I just finished up installing some OBX stainless headers on my H2. Not too bad of a job after I managed to get the junk GM hardware off.

History; My H2 developed an exhaust leak at the drivers side manifold at 54k miles. All GM would offer me is 10% off their book labor time to help out. The dealer estimate worked out to be $1800 including parts just for the one side. After the shock wore off, I figured I'd give the repair a shot myself. The exhaust manifold developed a leak after the two rear bolts had the heads pop off. The passenger side was fine, no leaks, but decided to change it out as well.

Parts needed:
1.Headers (I used OBX SS that I found on Ebay)
2.Header bolts for LS style motor (found mine at Summit, Gardner-Wescott p/n 56406-HSP)
3. Grade D Hardware (for attaching the header to the H-pipe); Qty 5, 3/8's - 2 inch; Qty 1, 3/8's - 1.5 inch, plus associated washers and self locking nuts. I used two washers per, one on the top and the other on the bottom, qty 12 washers total.

Tools needed for manifold to H-pipe connection:
1. 1/2 breaker bar and long extensions
2. Deep 15mm (removing stock hardware) and 9/16's (for installing 3/8's replacement hardware) sockets for 1/2 drive and a 9/16's wrench.
3. Penetrating spray (recommend hitting the hardware with the spray a couple of times in the days leading up to the removal to allow for the spray to penetrate and loosen).
4. Important, when backing off the original nuts, make sure you reverse your drive after a few turns and clean the threads on the studs. Otherwise you'll strip the threads out of the nuts. The metal in the original attaching hardware is very soft and is easy to destroy.

Tools needed for Manifold removal:
1. Important, get a very good pair of vise grips
2. 3/8's drive and breaker bar, possible use the 1/2 breaker
3. 13mm socket for the manifold bolts
4. 10mm socket for the positive electrical box bracket that needs to be moved to gain access.
5. Flat head screw driver to remove the intake air tube (need to remove for passenger side only)
6. Pair of pliers to aid in removing the spark plug wires and the oil dipstick tube.

Notes:
Dipstick tube must be removed for the passenger side only. Remove the 15mm bolt from the dipstick bracket first, then the dipstick tube can be pulled out, but it takes some wiggling. Recommend a pair of gloves to help with this.

I reused the stock metal gasket that was installed from the factory. Its a good piece and it sealed up nicely again after installing the headers. Also reused the gasket in the stock H-pipe. If your H2 has 100k miles or more and still on the original spark plugs, this would be a good time to replace. Make sure you use anti-seize on them.

I included some pictures of the manifolds I removed along with the stock attaching hardware. If you look at the pictures, you can see where three of the manifold bolts are missing their heads. Two were missing prior to the install on the drivers side. The third tore off in my socket when I was removing the passenger side manifold. The bolts are very soft so you need to be careful. This is when the vise grips come in handy. I had to use those to back the broken bolts out of the heads. Get them on there tight to get a good grip.

The install was very easy with the new hardware. Total time took 6 hours for both sides.

If you need any additional info, ask the questions here and I will try to answer.

Thx and GLTA
Eric

 

For anybody looking for gas mileage improvements, my H2 was averaging 11.5 mpg in city and now its 12.2 mpg city after installing the headers.

 

How do you like them? Sound improved Im sure. Hows the throttle response? I have some shorties laying around my garage but havent gotten around to installing them. Ive often wondered about that brand. Ive used Hooker LT and Kooks on my camaro and I have Pacesetters LT on HD pickup.

 

thanks for posting the pictures

 

Didn't notice much of a difference in sound (except being quieter due to the stock manifold leaking). The off-idle throttle response was much improved. Gas mileage improved.
The OBX headers looked like they were put together pretty well. The welds were nice and there wasn't any splattering or trash inside the runners. The flanges were thick and everything bolted right up without any alignment issues.

 

yea i keep on seeing those headers on ebay the long tube and for the price was wonering if they are worth it or not , how are they now that you have had them for awhile , would you say the performace was better could you feel the differnece in gains

 

The dealer estimate to me was 10 hours labor at $110/hr and approx $600 in parts.
My headers are holding up well. I live in florida so i can't say how they would hold up to corrosion. can't be any worse than what was on there.
My gas mileage improved and i could feel a difference in the seat of the pants with the midrange power

 

Are these headers mated to an aftermerket exhaust as well?

 

No, it's bolted to the stock exhaust.

 

Were these shorty or the OXB with high flow cats