Belt slip or speed limiter?

So, I had to take my wife into town so she could pick up her truck today, and on the way home tonight.....

I'm in my '07 4x4 RCSB SC 5.7(TRD/Maggie w/TRD tune) completely stock except for blower and fit kit, just turned 189,000 miles..
My wife is in her '16 ram 2500 w/6.7l Cummins and 6speed manual, straight pipe, def delete, some kinda tuner and a bunch of other shit, 110,000 miles.

We're basically in the middle of nowhere, nobody else on the four lane highway, I'm tired of being behind that black lung POS, so I get in the left lane , pull up beside her and she tries to not let me around.lol
I pushed the go pedal and proceeded to finish what I started, and when I was getting up there in speed ,it was kinda like the ECU was cutting power.
My truck pulled hard and no knocking, no pinging, no CEL, I wasn't quite WOT.
My question is,
I thought the TRD tune turned off the speed limiter?
Could I have been having some belt slippage?

 

TRD tune doesn’t turn off the speed governor. Bullydog does plus it gains 90hp and 50tq to the rear wheels over whatcha got

https://youtu.be/9Gnb6_PUfg4

https://youtu.be/pJjnSoekN5Y
http://dirtydeedsindustries.com/product/bully-dog-gt-platinum-tuner/

 

Thank you for the links, I'll check them out.
The TRD tune had to at least bump up the speed limiter? because I was over the last number on the speedo still had a little bit of pedal left, just didn't seem to have any pull left when I pushed it to wot.

And if that's true what you said about the BD tuner, 90hp&50tq, Holy shit Batman!!
What a fuckin Beast!
I was talking with a local tuner that just got HPtuners. Unfortunately @ViktorG stopped doing remote tunes because I wanted to try his tune.
Sounds like a BD might jump to the top of the want list.

 

The TRD SC tune has the speed limiter set at right around 120-125 mph

 

Thank you Viktor. thats what I was feeling in my accelerator was the ECM pulling power, Damit!
Looks like I'll be getting a BD unless you start selling remote tunes again?
Did your tune remove the speed limiter?