2022 refreshed model 6.2L

[Bowzer]

Have a new 2022 refreshed model 6.2L TB. Would anyone have any information on removing the exhaust but leaving the cat and it dropping your fuel mileage SIGNIFICANTLY. I had a early model 2022 AT4 with same engine same tranny and same gear ratio but that thing was absolutely incredible on fuel I could get 10L/100km on the highway and at most 14L/100kms in town . I have a 14’ aluminum trailer and pulling it with my sxs I was averaging 18-20L/100kms. It came with the performance package so had the true dual borla exhaust. My new truck I’m lucky to get 14/100 on the highway and 17/100 in town and pulling the same trailer I’m at 30/100. I’m not aggressive at all on take off and do 105kms/hr on the highway and drove the same with my AT4. I don’t feel that it’s hitting 10th on the highway when pulling my trailer and I know my AT4 did. I took it back to the shop and they had a service tech and a transmission tech take it on the highway with my trailer hooked to a computer and everything checked out. I had 30,000 kms on my AT4 when I got rid of it and didn’t notice a change in fuel mileage right from new and I do believe in that fuel mileage increases after break in but did not notice anything with the AT4. My new truck has 7000 kms on it and it’s been the same in fuel mileage from day 1. I know it’s a big engine and I didn’t buy it expecting it to be good on fuel but the difference between the 2 trucks is disgusting. Only thing I did to the TB was removed the exhaust but can’t see that being the issue especially with my AT4 coming factory with performance exhaust.
Any opinions would be greatly appreciated. My dealer told me to get a cold air intake but in my understanding that will allow the truck to breathe better on both ends and in turn be even worse on fuel mileage or am I completely wrong on this.
But man oh man you can’t beat the performance of this engine

 

[Kentrucky TB]

Did your AT4 have DFM and the refresh not? That would explain it if that’s the case.

 

[Bowzer]

The AT4 had AFM and the new TB has DFM not sure if there’s a difference but my understanding is there both extremely hard on heads in the engine and tried to get both vehicles deleted but was told they can’t

 

[L39 Albatross]

The AT4 had AFM and the new TB has DFM not sure if there’s a difference but my understanding is there both extremely hard on heads in the engine and tried to get both vehicles deleted but was told they can’t

This forum is full of comments on deleting AFM/DFM with an aftermarket Pulsar LT. I have one on my 2021 TB and it shuts off auto stop/start too. Yes, doing this DECREASES your fuel mileage. Yes, adding a cat back exhaust DECREASES your fuel mileage. Adding bigger wheels/tires DECREASES fuel mileage. Your truck is turned by GM to maximize fuel mileage, not performance. If you choose to increase performance, you do so at the cost of fuel mileage. I have the same 6.2 with a Pulsar LT which shuts off my AFM and auto stop/start, an oil catch can, Cold Air Induction cold air kit and a massive, killer sounding AWE Performance cat back exhaust. On highway with cruise on (no trailer) I average 15mpg. City is worse. I look at it like this....if I cannot afford the fuel for my truck, the insurance, truck payments and maintenance costs, then I really cannot afford the truck. The 6.2 drinks fuel because of it's performance. I have a video of my 6.2 TB pulling a semi truck out of the mud with 42,000lbs of product in his trailer. I'll take the hit in fuel economy for that kind of torque/power.

 

[Baz]

The AT4 had AFM and the new TB has DFM not sure if there’s a difference but my understanding is there both extremely hard on heads in the engine and tried to get both vehicles deleted but was told they can’t

2022 AT4 6.2 wouldn’t have AFM… 6.2/10-speed has always been DFM.

 

[Bowzer]

This forum is full of comments on deleting AFM/DFM with an aftermarket Pulsar LT. I have one on my 2021 TB and it shuts off auto stop/start too. Yes, doing this DECREASES your fuel mileage. Yes, adding a cat back exhaust DECREASES your fuel mileage. Adding bigger wheels/tires DECREASES fuel mileage. Your truck is turned by GM to maximize fuel mileage, not performance. If you choose to increase performance, you do so at the cost of fuel mileage. I have the same 6.2 with a Pulsar LT which shuts off my AFM and auto stop/start, an oil catch can, Cold Air Induction cold air kit and a massive, killer sounding AWE Performance cat back exhaust. On highway with cruise on (no trailer) I average 15mpg. City is worse. I look at it like this....if I cannot afford the fuel for my truck, the insurance, truck payments and maintenance costs, then I really cannot afford the truck. The 6.2 drinks fuel because of it's performance. I have a video of my 6.2 TB pulling a semi truck out of the mud with 42,000lbs of product in his trailer. I'll take the hit in fuel economy for that kind of torque/power.

Like I said the AT4 came stock with the borla exhaust and was incredible on fuel. My TB all I did was remove the exhaust the cat and everything else is factory so how can that make that big of a difference. My post was not meant to complain about fuel mileage but to try determine what the difference is between my 2022 AT4 and my refreshed model 2022 TB with same motor tranny and gear ratio and yet not even close in comparison with fuel mileage.
Any response that can help me determine an answer to my question would be greatly appreciated and if there is anything I can do to?

 

[L39 Albatross]

I had a 1991 GMC Syclone I used to drag race. When I was young and dumb, I would unbolt my exhaust system to race believing it would increase my performance. Come to find out, the engine needed a certain amount of back pressure or it lost performance. Your Borla exhaust on your AT4, much like my Syclone exhaust, was specifically tuned to your engine. It added the exact amount of back pressure on your engine GM determined was best for fuel economy. When you removed the exhaust on your TB, you removed the back pressure and allowed your engine to "breathe" better. This is what dropped your fuel mileage.

 

[Bowzer]

I had a 1991 GMC Syclone I used to drag race. When I was young and dumb, I would unbolt my exhaust system to race believing it would increase my performance. Come to find out, the engine needed a certain amount of back pressure or it lost performance. Your Borla exhaust on your AT4, much like my Syclone exhaust, was specifically tuned to your engine. It added the exact amount of back pressure on your engine GM determined was best for fuel economy. When you removed the exhaust on your TB, you removed the back pressure and allowed your engine to "breathe" better. This is what dropped your fuel mileage.

Thank you very much for your response. This is something I was leaning towards but wanted a second opinion from someone with experience before I attempted changing anything else.
Greatly appreciated!