Best tuner for L86 6.2L / 8L90

[2018GMC]

Who do you recommend to have my truck tuned? I’ve used blackbear for my older trucks but they tell me they can’t tune the 8 speed transmission. I’d like to get both engine and transmission tuned. Truck is like new with only 24k on it and I purchased it new in 2018. I have a plug in AFM disabler but still use AFM on on long interstate trips. It’s always disabled around town though. 
 

2018 GMC Sierra crew cab 6.5’ standard bed 4x4 max tow package 3:42 gearing 6.2L + 8L90. 
 

Completely stock except for stock muffler and flapper removed. Replaced with magnaflow 14909. Stock intake removed and replaced with AFE Momentum HD. 
https://afepower.com/afe-power-54-74104-momentum-gt-pro-5r-cold-air-intake-system
 

Or should I just leave it alone? It occasionally tows my enclosed 4k lb trailer and max I’ve towed with it is 6k lbs. truck is rated at 11,700 lbs. 

Edited February 13, 2025 by 2018GMC

[CamGTP]

Pretty sure the only tuner than can tune the transmission is HP Tuners. So you'd have to learn how to tune to use that. I use HP Tuners but I've had it for 13 years now, so my experience is a lot more with it.

 

Or find a shop that can tune it using HP Tuners. It won't be cheap no matter which way you go. The cost of HP Tuners and the credits required to tune both will be a chunk of change and you need to have the TCM unlocked through HP Tuners to tune that.

Edited February 13, 2025 by CamGTP

[TNTSierra]

16 hours ago, 2018GMC said:

Who do you recommend to have my truck tuned? I’ve used blackbear for my older trucks but they tell me they can’t tune the 8 speed transmission. I’d like to get both engine and transmission tuned. Truck is like new with only 24k on it and I purchased it new in 2018. I have a plug in AFM disabler but still use AFM on on long interstate trips. It’s always disabled around town though. 
 

2018 GMC Sierra crew cab 6.5’ standard bed 4x4 max tow package 3:42 gearing 6.2L + 8L90. 
 

Completely stock except for stock muffler and flapper removed. Replaced with magnaflow 14909. Stock intake removed and replaced with AFE Momentum HD. 
 

Or should I just leave it alone? It occasionally tows my enclosed 4k lb trailer and max I’ve towed with it is 6k lbs. truck is rated at 11,700 lbs. 

I did a can-tune/handheld tune from Hypertech called the Spectrum. It does everything EXCEPT tune the transmission. It does allow you to mess with the TQ converter, but I really don't notice a difference on the tranny. The K2 transmissions are LAZY in down shifting. But I did notice a nice improvement on HP/TQ. The truck is quicker off the line and accelerates quickly for just a Corsa Catback exhaust on it. I got it on sale at Realtrucks.com during a weekend special for $200 and change. Basically same price as a Range. It also allowed me to adjust the speedometer to 130 mph and adjust it for my 22 inch tires.  I have noticed ever since Covid, HP Tuners has "raised" their prices considerably since I had my last brand new 2018 SLT 6.2L when I called them back then.  Hypertech was very good over the phone with any questions, and updated my Denali through email very quickly onto the tuner when I got it. Good Luck with your decision  

[2018GMC]

I recently added this which greatly improved throttle response. I purchased this and the intake used as the new prices are ridiculous.
 

https://afepower.com/afe-power-77-14003-sprint-booster-power-converter

[ftwhite]

I had Black Bear provide me a tune, and I also later had a local shop do an HP Tuners tune on a dyno. I learned a lot about tunes on the second, but the improvements to torque and horsepower were not significant enough to make much driving experience change. I currently have the HPTuner tune applied, but felt the Black Bear did a little better job with dialing in the "shift points" using what's available outside unlocking the transmission. 
So, it depends if you have a local shop with dyno, and/or want to get deep into settings; or if you want more of a DIY "plug and play". I highly recommend Black Bear for the later. I have used them on 3 GM trucks/suvs, and no complaints. 200k+ miles combined easy with no troubles or dealer issues. Dealer does "flash back" and report it as an update when they have done work.   

Edited February 13, 2025 by ftwhite