I'm getting ready to install a set of Kooks 1 7/8" headers on my 2011 6.2L GMC Sierra 4wd Crew Cab.

Is there a step-by-step write up anywhere? Anything tips?

Thanks in advance!

 

It is incredibly easy. Pull your spark plugs, support your trans and either drop one side of the crossmember (requires pulling nuts from trans support and removing two passenger side bolts and one drivers side bolt while loosening the other), disconnect the cat back with the one ball flange, unhook the electrical connections for each O2 sensor, unbolt the 3 nuts off the studs for each manifold and drop the Y pipe out. Go back to the top and pull the manifolds. Both of my long tubes pushed through from the bottom (with the drivers side requiring some twisting and shoving). Bolt them in place with whatever you choose for gaskets. Take your front O2 sensors from the old y pipe and put the bungs on the header and connect the electronics. Get your passenger side of the Y pipe in place and connected to the header loosely as well as connected to the cat-back. Then put the drivers side of the y into the passenger side after you have the clamp on. Get it connected to the drivers header and then massage everything into its final place and tighten. Put the rear O2s in and replace the trans crossmember as it was. Reinstall your spark plugs and check wire clearance. I replaced my wires because I didn't like the clearance. But basically you are done.

 

You will want to try to use some form of penetrating oil on the manifold studs or it is likely they will not come loose (like mine) and you will end up cutting out your y pipe. If you are okay with doing that to start with, you can skip lowering the crossmember in the first place. Obviously my above instructions were assuming you want to keep the system in tact.

 

To add to what was already posted:
- If you lift the vehicle by the frame, remove the front wheels and fender skirts you'll have easy access to the manifolds.
- The spark plug wires may be difficult to remove. Giving them a twist on the spark plug end can aid in removal.
- I've used new factory exhaust manifold gaskets on two vehicles without leaks.
- Use new exhaust manifold bolts; GM bolts come with loctite preapplied. I've seen quite a few high mileage trucks with a broken exhaust manifold bolt; better to replace them now than drill them out of the heads later.
- I routed the power wire to the starter toward the front of the truck to keep it from contacting the right side header. The cable was long enough to do so without removing it. I also trimmed the "tabs" off of a couple of my spark plug wires for additional clearance.

 

^^ what wannablaze said. Its soooooooo much easier to remove the wheels and inner fenders. It will beat a hurting back. Caused bu being hunched over the fenders and stretching to reach all the bolts. The hardest bolt was drivers side rear.