Installing ARH LT headers on AWD Sierra Denali
 

I just got an e-mail this morning from Nick @ ARH that my headers are being shipped out today so I'm planning to install them next weekend. They are 1 7/8" primaries with the ORY with 3" into 3 1/2". (I sized them big because I use Nitrous and I intend to instal a cam in the future)
Has anyone on here done this installation before on an AWD? If so, is there anything that you can do to make the install easier? Any links to install instructions, etc.? From looking under my truck it looks pretty tight on the left side in particular with the front driveshaft and transfer case, so I'm sure it might be a challenge.
Also, will these necessitate a retune or will the ECU relearn after a bit of driving?
Thanks.

the install with me went smooth... fit absolutely perfect! can't get better quality then these guys...

easy job,
take the front wheels off and fender liners out, way better than climbing over the fender.

they will likely set some codes

I can't really comment on the NNBS trucks, but on my '01 C3 when I installed the Dynatech's, I did find that it gave me a little extra room by disconnecting the front driveshaft from the differential and pushing it over out of the way.

Thanks very much for your input guys. I will let you know how the install goes...

They were the easiest thing to install that i have ever installed. The only question i had were with the cooler lines for the tranny but that was an easy fix. Just bent them out of the way a little bit. Other than that, very clean and easy to install.

What do you do about codes? Does this require a major retune, or can I just delete the DTC? I will most likely have to use HPT to turn off the rear O2 sensors anyways, since I have the ORY and I'm not sure if wheatley turned off the rear O2 sensors when he did my tune. I'm installing the headers this weekend, so I'll report back on the install and results...

if you have hpt just turn off the report for the codes in the dtc list.
i was freaked when i put my headers on but i did a lot of researh and it's all good.
don't turn off the sensors, just turn off the code reports. i think its 1133/53 for rear sensors and 1120/30 for front. don't have laptop here to check
if you turn of the sensors you may not be aware of other cat issues if the come up
you can tune for the headers but the stock pcm will also somewhat adjust so it's not a panic

I installed the headers yesterday. Took me about 6-7 hours total (not counting interuptions and searching for tools etc.) These are by far the best fitting headers I've ever installed, including the custom made Lemons BBC headers on my 2000 Camaro SS race car. The hardest part was getting the rear bolt on the left header tightened and I had to replace the collector bolts on the Y-pipe to flex-joint connection because one of them wrung off. I aslo had to take the sawzall to the factory Y-pipe to avoid dropping the trans crossmember. It did have a DTC, but I took it to my tuner friend this morning and he turned off the two rear O2 sensors and cleared the DTCs. I have to do that since I have the ORY without cats. I've also installed an Innovate W/B sensor in place of the right rear factory O2 sensor and a LM2 to monitor AFR.
The truck is much louder now, and besides the crackle of the headers, it really has a growl when you step on it. Some of my friends are even swearing that I've changed the cam because it sounds so different. Unfortunately, I'm leaving town on Tuesday for most of June, so I won't get to test it at the track anytime soon, but when I return, I will and report back with the results. Thanks again for everone's input.

Sounds good, enjoy