The current-generation GMC Sierra AT4 – whether in pre-refresh guise or refreshed form for the 2022 model year – offers impressive off-roading capabilities thanks to a list of rough-stuff extras and equipment. Now, we’re getting an earful of the AT4’s V8 growl thanks to an upgraded cat-back performance exhaust system, as featured in the following exclusive GM Authority video.
The official title for the optional exhaust upgrade featured here is simply Cat-Back Performance Exhaust, tagged with RPO code WBC. The system is available on all 2022 GMC Sierra 1500 trim levels with the exception of the new Sierra AT4X, which features a unique exhaust treatment that’s tucked underneath the rear bumper for improved off-roading clearance.
To note, the Cat-Back Performance Exhaust system is offered as an LPO-level option, which means it is delivered to and installed by the dealer, rather than installed at the factory when the vehicle is initially produced. Pricing is set at $1,895.
The new pipes connect to the naturally aspirated 6.2L V8 L87 gasoline engine, rated in stock form at 420 horsepower at 5,600 rpm and 460 pound-feet of torque. With the new, free-flowing exhaust in place, we would certainly expect a few extra ponies to be liberated from the V8. And extra ponies there: the system delivers up to a 13 horsepower improvement at 5,600 rpm and up to eight additional pound-feet of torque at 4,100 rpm compared with the production exhaust system, thanks to the 40 percent reduction in back pressure at 335 g/s at 600 degrees Celsius. Note: the estimated power is based on SAE test procedure J1349.
And of course, the new system also makes a substantially improved sound, as heard in the following exclusive GM Authority video. Right at startup, the exhaust gives a nice burble, rumbling to life before falling into a steady but noticeable idle. A few stabs of the throttle emit a smooth combustion note, with a tone that’s deep, but without any drone. No doubt, this exhaust upgrade adds just the right amount of aural punch to the GMC Sierra AT4 (or any compatible Sierra, for that matter).
The system is a bolt-on cat-back and includes everything required for complete installation. it’s also emissions-legal in all 50 states and will not void the New-Vehicle Limited Warranty.
As a reminder, the GMC Sierra AT4 is also available with the 3.0L I6 LM2 turbodiesel Duramax, rated at 277 horsepower at 3,750 rpm and 460 pound-feet of torque at 1,500 rpm. Under the body panels is the GM T1 platform, while production takes place at the GM Silao plant in Mexico and GM Fort Wayne plant in Indiana.
Oh, and for particularly detail-oriented readers, this is a 2022 Sierra AT4 Limited, meaning it’s not the refreshed model. That, however, doesn’t change the sound one bit.
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Comments
Think they should have done a slow pull away from a stop
American v8s have that amazing low rpm lope and that high rpm sound.
But what I like the most ISS the low rpm just off idle sound.
Notice how unstuffed exhaust gets more power. It will also get you better mpg if you don’t use that power…
No need to have interest in exhaust sound when electric is going to be mandatory. Vendors and OEMs are pulling out of SEMA like mad. No more of Ford’s drifting Mustangs.
We are moving to an automaton, generic world. Little boxes for housing and electric cars. The Japanese already have sliding human sized drawers for motels. Good luck if you have a prostate issue and need multiple relief at night.
Maybe electric cars will offer human discharge features. A thought for the options engineers.
“The Japanese already have sliding human sized drawers for motels. Good luck if you have a prostate issue and need multiple relief at night.”
The Japanese are far more efficient than you think and already figured out the solution. Their solution is to elevate the legs a few hours before sleeping to drain the fluid out of them, and also special underwear that squeezes them.
Is there any cat back exhaust for the AT4X?? Thanks.
No, not as of right now. That said, it might be technically feasible to get the system seen here installed on the AT4X by swapping the rear bumper for an AT4 unit, thereby delivering the cutouts for the exhaust tips. This swap is easier said than done, however, due to the rear parking sensors.
Performance exhaust combined with no more bad valve lifters one can hope for. But with all the complaining about failed valve lifters that issue has not seemed to have been addressed satisfactory to very many ICE owners yet. Will a performance exhaust expedite a potential lifter problem if the owner is rooting on it more often. Myself I have a tenancy to root on my musclecar more when I open up the cutouts on my exhaust. But I also have lifters from 1987. Just saying hopefully no one else has anymore lifter failures on their new vehicles.
Thanks for the listen. Does not compare well at all in sound with the Hooker single outlet unit featured above. This GM unit is too metallic and high-pitched. People appreciate a full, throaty sound from their accessory exhaust systems.