Performance Upgrade Package

[brothernov]

I recently purchased an AT4 withe the 6.2L.  I love most everything about it, but I'm considering adding the GM produced/installed cold air intake and cat-back exhaust.  All I'm looking for is a little more rumble, not trying to announce to the world I'm driving by or wake the neighbors when ever I pull in.  There's very little in terms of reviews or vids out there to give me some insight.  What do you guys think, Is the dealer's performance upgrade offering on the "tame" end of intake/exhaust mod offerings?  Will it be an annoyance inside the cabin while driving down the highway?  I know these are pretty subjective questions, and thank you in advance for any insight you can offer.  

[OnTheReel]

The exhaust isn’t obnoxious at all but certainly a noticeable difference over the stock exhaust which is basically silent at all engine speeds.

 

If I’m honest, it was a little louder than I expected for a “factory” part and it took a little getting used to. Overall, I have no complaints there because it calms down VERY nicely at cruising speeds. There is no drone at all and sounds pretty much the same as it did before on the highway. Stop and go, in-town type driving you do hear some more rumble in the cab, but it’s not to the point of having to speak up or anything.

 

Cold starts are on the loud side until the idle drops but that’s the only time I hear it from in my house. 

 

I think it’s a very nicely designed kit and I’m very happy with it. The performance boost is a great plus, as it’s good for 13hp on the 6.2.

 

Videos are very tough to judge how it sounds. I am going to make more shortly but for now I just have the two vids below. Obviously a Chevy, but the same exhaust part # and engine you have.

 

 

 

[Jon D]

I did both and am happy with the outcome. Much better sound and the truck just feels a bit more lively. 

[SierraAT4]

This video convinced me to buy one: 

 

[brothernov]

Thank you guys so much for the feedback.  I'm going to order it tomorrow!

[Rduatctt]

I installed both on my Denali with the 6.2. It was a little loud for me so I added resonators just prior to the tips and that toned it down a bit. I wanted to know it was a 6.2 but did not want it too be obnoxious 

[brothernov]

Would it make any sense to only add the cold air intake, or only the exhaust?  As I type it it feels like a dumb question, if I increase the air in I'll probably need to increase the trucks ability to expel it, but I know practically nothing about exhaust systems.

[Black02Silverado]

19 minutes ago, brothernov said:

Would it make any sense to only add the cold air intake, or only the exhaust?  As I type it it feels like a dumb question, if I increase the air in I'll probably need to increase the trucks ability to expel it, but I know practically nothing about exhaust systems.

You can att the CAI by it's self but to get the most benefit the exhaust is also needed. 

[Schmoe]

I just had the performance exhaust placed on my 6.2 AT4 yesterday. Love it. Did not do CAI. I just couldn’t find anything that definitively said it was worth the money. I’m not opposed to doing it (or maybe one of the other aftermarkets) in the future if it will improve performance/ mpg’s. The exhaust itself did everything I wanted it to for the sound. 

[OnTheReel]

2 hours ago, Schmoe said:

I just had the performance exhaust placed on my 6.2 AT4 yesterday. Love it. Did not do CAI. I just couldn’t find anything that definitively said it was worth the money. I’m not opposed to doing it (or maybe one of the other aftermarkets) in the future if it will improve performance/ mpg’s. The exhaust itself did everything I wanted it to for the sound. 

Same here. The exhaust is good for 13hp according to GM. No numbers for the CAI alone, but GMC reports that the CAI AND exhaust add 15hp in the AT4 performance package. That would leave 2hp to be attributed to the intake.

[Schmoe]

21 minutes ago, OnTheReel said:

Same here. The exhaust is good for 13hp according to GM. No numbers for the CAI alone, but GMC reports that the CAI AND exhaust add 15hp in the AT4 performance package. That would leave 2hp to be attributed to the intake.

Yeah, a lot of my decision was based on your posts, lol. So, if anyone else is curious, I have found OnTheReal’s info to be quite accurate and reliable. ??

[OnTheReel]

Thanks! I don’t mean to repeat myself about it, but the same questions keep popping up about their CAI. GM could squash it by posting the numbers themselves, but I suspect they don’t for a reason...

[Trwtow]

anyone got the part number handy I have a 6.2 hicountry gonna try just the exhaust thanks

[BLACK AT4]

Save yourself the money on the GM Cat Back System. The restriction is the flapper valves. Each one has a 1.25" restriction when wide open. I have posted the picture of the flapper valve many times on this site. I will post one more time. I cut both off and installed a Magnaflow 12909 and left the resonators because they do not restrict the flow. The entire cost was less than $200 including the labor at the exhaust shop.  here is the muffler on  Amazon  https://www.amazon.com/gp/product/B000XQM1LC/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

 

The Magnaflow is a straight through muffler, You can hear it on the freeway but after about 400 miles it quiets down. 

 

[Jmonty]

22 hours ago, BLACK AT4 said:

Save yourself the money on the GM Cat Back System. The restriction is the flapper valves. Each one has a 1.25" restriction when wide open. I have posted the picture of the flapper valve many times on this site. I will post one more time. I cut both off and installed a Magnaflow 12909 and left the resonators because they do not restrict the flow. The entire cost was less than $200 including the labor at the exhaust shop.  here is the muffler on  Amazon  https://www.amazon.com/gp/product/B000XQM1LC/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

 

The Magnaflow is a straight through muffler, You can hear it on the freeway but after about 400 miles it quiets down. 

 

Any drone? How much louder did it get?