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    2021 AT4 6.2L

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  1. I’d be curious to see some technical data showing distances, temp, etc for braking under various conditions with stock vs the Brembo upgrade. Might even add a 3rd comparable of stock with SM pads. And if one were to get crazy a 4th showing the Wilwood option. I don’t have “direct” comparisons. However my 6.2 AT4 feels a little weak to me also. The last personal truck I had was a 2014 Dodge Ram 1500 Sport 4x4 with 5.7 Hemi, 8-speed and 3.92’s. Very comparable to the AT4 despite a 7 year gap. Those brakes were better. My last company I worked for gave me a Ford Explorer SLT. Brakes were really good in it. I make no qualms or excuses. I tend to drive more aggressive than others but not crazy or unsafe. My driving style didn’t change amongst the last 3 vehicles. My wife’s 2019 Armada is probably worst than the AT4 but it’s due for a brake job. Don’t take me wrong, I love my AT4 but I would appreciate a significant brake upgrade. And from my hot rod days anytime Brembo or Wilwood comes up, it’s going to be a big expenditure. I don’t mind to spend the bucks if the performance is really all that.
  2. Here is a great example of nominal vs actual sizes. I did the math earlier to show nominal size. The actual size is pretty close but a smidge taller and wider. Once you determine the actual dimensions of the OE tire currently installed, you can determine the true delta between the two. Effectively the delta is what makes it compatible or not. Assuming you don’t lift, trim, use spacers or buy new rims with different offset then the geometry of available space remains constant. This is why one guy may give a thumbs up to a certain size and another says it won’t fit. I might even add how you use your truck matters. If it’s a street queen then you can likely push the fringe a little more but if you off-road and need full articulation then available space and usable space under flex becomes more critical.
  3. RPO = Regular Production Option GM uses RPO codes to identify the various options used in each vehicle build including the stereo used, paint color, seats, etc. Some RPO codes even find their way into model identification such as AT4, Z71, Z28, Z06, ZR1, etc. You can find some of the codes on the VIN stickers in the door jamb or under the hood. Also you can ask your dealer for a list of RPO codes for your specific vehicle by VIN. Once you have this info you can determine if you have the IOS radio. This is the RPO of the mid grade radio without navigation and what the previous Kicker part number says is required to be compatible. So if your RPO list shows and IOS radio, then the part is compatible. By the way I found this thread for a 2019 particularly interesting. Apparently IOS owners can buy an SD card and have the computer reprogrammed to get factory navigation which is identified by RPO code IOT. I am curious if by chance you have navigation and/or do the upgrade so you effectively end up with an IOT, is the kit (with DSP/amp) still compatible? It says for IOS radios so does the programming to enable nav somehow make it incompatible as it’s really an IOS with card + programming?Or does the true IOT yet have other things undiscovered that make it truly incompatible? Maybe the better question, do you have nav and effectively the IOT unit? If so, maybe this is your “why”. Whatever the answer, I would frame your question to the dealer differently so you get better results.
  4. Double check you have the correct radio in the non-Bose setup. Also, here is a video that my be helpful if you decide this kit will work. Kicker part #19417166
  5. As others noted, bigger meats increases rolling resistance which decreases MPG and also puts some marginal amount of extra wear/tear on the vehicle. At least in theory, right? In reality, I’ve swapped tires to much larger sizes without a concern about longevity concerns but that probably comes down to personal tolerance for risk. In my experiences I never saw failure but I didn’t keep said vehicles > 100k miles either. This calculator provides an option to compare tire sizes and includes revolutions per mile to calculate speedometer variances. It’s pretty minor as you will see. At 80-90mph there is about 3mph variance. The variance decreases or grows in direct relation to your speed. Most hand held tuners can reprogram the computer for different tire sizes so it all reads correctly. The dealer can also but I suspect that will be a costly ordeal for small benefit. https://tiresize.com/calculator/
  6. I’m mobile but you need to check ACTUAL dimensions for the tires listed. However, using the nominal measurements, it appears there is about a 1” height and 3/4” width difference. The variance in actual vs nominal may be less or more as every 275/70 or 285/70 don’t have identical dimensions. 265/70/17: 265 x 0.70 / 25.4 x 2 = 14.61” + 17” rim = 31.61” tall 265 / 25.4 = 10.43” wide 285/70/17: 285 x 0.70 / 25.4 x 2 = 15.71” + 17” rim = 32.71” tall 285 / 25.4 = 11.22” wide
  7. Thanks, I wasn’t aware there was a wired and wireless option. Seems almost silly for it to not be wireless in todays world. Anyhow, I realize you aren’t looking to add a wireless charger but this video shows you how to disassemble and tap into the rear facing USB ports in the center console, which may be a solution for you. Thinking about it I’m curious if you could use the dongle to connect the wireless charger and trick it into working. Didn’t post for that purpose but rather just an idea.
  8. I’ve read a few threads about CarPlay requiring the wire. I *only* run wireless in my 21 AT4. Didn’t do anything special to my knowledge. It just works. Is it a trim level difference, or something else?
  9. My AT4 didn’t come with either, and I am considering an upgrade. Been awhile since I did speakers & amps. The factory unit seems expensive. What is everyone’s take on the bang for the buck factor?
  10. Reading through this massive thread and something I keep seeing that I think needs clarified is tires are NOMINALLY sized, meaning not all 33x12.5’s or 295/60/20 or X/Y/Z tire is the same. You have to look at the specific dimensions for each manufacturer & brand of tire. For instance some nominally sized 33’s may have actual dimensions of 32.5 or less. Others may be slightly > 33. Depending how tight your clearance is (or isn’t) you may end up with rub issues over these minor differences.
  11. Recently purchased a 21 AT4. Really like the truck but want to make a few changes. One of the first is leveling the truck so it doesn’t have the raked look. I see several leveling kits available that are basically spacers. Read another post elsewhere that stated the spacers essentially caused long term wear/tear. I like the factory ride of the truck and want to maintain it. Also I’ve owned a Wrangler in the past and did budget boosts/lifts which were spacers and finally a true suspension lift which rode better but was never quite as good as factory. I am not interested in going extreme but just want a good quality level. Hoping some of you can share your experiences, recommendations, etc so I make the right choice.
  12. I believe what you want is a factory service manual, or FSM. Harder to find on newer vehicles. Last one I had I bought a week subscription and printed to PDF everything. It was a huge PITA, time suck and not something I would do again. At one point I thought there was a vehicle specific FSM available for a few hundred bucks. But that’s been a few years since I searched for that option.
  13. I have a 21 AT4 with the 6.2 and 10-speed. No issues with my seat adjusting to a comfortable level or any issues with the parking brake. No other issues at this point either but it’s < 2 months old. My last 2 vehicles before this was a 2010 Dodge Challenger RT with 6-speed manual and 2014 Ram with auto 8-speed (and 3.92’s). Both with the 5.7 Hemi variant. I mention these for a few reasons. First, anything with cylinder management is a complication that continues to hinder IMO. Tuners adapt for the people that want to push the envelope but you are better off without it. Secondly, my Ram was a *dream* to drive. I initially had doubts with the 8-speed but in reality it was a Mercedes unit and coupled with the 3.92’s and 5.7 was a powerhouse! The only thing I couldn’t outrun was a gas station, lol. Average driving was about 13mpg with towing dropping it to the 9mpg range. Moving to the GM platform this go round, I found it annoying I couldn’t get 3.73’s. But I love the 6.2. I drove the 5.3 and it didn’t have enough power for me. I may eventually change gearing but for now I’m good. I am glad it isn’t a 6-speed transmission as I don’t think I would have bought as it’s very noticeable to me now. FYI, I do mostly city driving but did manage to make a 4 hour trip recently and pulled about 24mpg and I was pushing 80+ most the way. I was pretty shocked to see the MPG that good honestly. Your question not only comes with potential preference and performance differences but also cost implications. Maybe in crazy COVID pricing you can sell your freshly purchased 2018 and move up without losing money but that is atypical. If you can do so then I probably would and jump to the 6.2 as well, assuming it still fits your budget. If it stretches your budget too tight or you lose money swapping I would be patient and consider other alternatives. There is always newer, faster and better just around the corner. Just ask all the guys holding out for the 2022’s, lol.
  14. Also new here. Wasn’t aware of this. What brand and model number is recommended?
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