That's what I was thinkin' but I'm no trans expert. I have heard of some junkyard 4l80's holding a lot I thought. A stock rebuild would at least insure it's new parts right?

 

Yea. The biggest thing is knowing what you have a piece of mind.

 

Yea, it's used and it's on a pallet, lol, so might as well make sure you only have to touch it once.

 

If it’s truly a known good transmission, I’d say run it.

 

Good advice on the trans. I had an '06 1500 GMC Sierra Z71 5.3L with a 4l60, and I put a Maggie MP112 on it when it was brand new. It took tons of abuse, but the trans blew around 80 - 90K miles. Aside from paint peeling off of the hood above the engine, the transmission was the only problem I ever had. GREAT TRUCK!!! The PD system was just the kit that Magnuson sold, too, nothing else was done to the truck. And it was their canned tune as well, and it still roasted tires and embarrassed BMWs and Mercedes-es everyday of its life.

Now I have a 2017 GMC Sierra 6.2L with the 8-speed, Magnuson TVS1900, Alky Meth, BlackBear Tune, ZPE GrpTec 2.9" pulley, smaller gates green belt, and Magnaflow 12909 muffler with no flapper. This truck is amazing off the line, but took WAAAAAY more tweaking and smaller pullies than the kit came with to get it to where my old truck was. Main differences are this truck is much nicer/fancier (obviously though since we're talking an 11 yr difference), this truck can hit much higher top speeds and not shake like it's scared to go over 80mph, BUT this truck can't react to a throttle smash when already going 30mph or so. My 2006 truck could downshift and get right into boost, but this new one doesn't like to downshift when I tell it to.

 

Find a better tuner.

 

I know, but my money was already spent. It's running great now, so I don't want to kiss those hundreds goodbye and spend 400-600 more. I know it could be tuned better, especially an in-person dyno, but surprisingly I don't have very many good tuners around me (a little northwest of Los Angeles) that work on trucks.

There's
Ray McClelland at Full Throttle Kustumz, but they're expensive <FTK Home Page - FTK California>
Eddie Rios at Addiction Motorsports, but he's more of a car guy <https://addictionmotorsports.net/>
Alex at New Era Performance, but they took three months to reply to my email saying they were backed up <https://neweraperformance.com/>

What I WISH could happen is have Atomic on here give me a tune and if it beats my current tune, I pay him. But of course there's no way to do that because people would just lie and not pay. I already have an AutoCal and HPTuners too.

Oh, and one of the big problems is that 2017 is the first year in which you have to pay HPTuners to unlock the transmission (TCM). I haven't done that, so I suffer a little with the stock GM trans tune. But even very reputable tuners say not to mess with the trans tune all that much, so I dunno.

 

Tune your trans, it's just as or more important when boosted. Your not shifting to stay in supercharger efficiency range...

 

Be happy to help!
Take a look at our supercharger systems. We have a limited lifetime warranty on our head unit.
We sell them as Tuner kits, $2,950.00 for our Silverado system.
TorqStorm Supercharger Kits for 1999 - 2006 Chevy Silverado

 

Great price. Damn hard to beat that!