[PoManNox]

No idea on the lag situation, but the vib sounds like the TSB you mentioned. I had both front CV shafts replaced recently on my 2021 equinox per that TSB for free from the dealer chain I bought my 2021 from used a month ago. I find my 1.5T, 6spd combo to move along nicely for what it is. I believe your Terrain has the 9spd, so that may account for the difference.

 

[PoManNox]

TY, did your dealer have to replicate the issue or took you on your word? And was it covered under the powertrain warranty?

They noted on the write-up that they test drove and confirmed.

 

[PoManNox]

As @repairman54 has noted in other threads, there is no turbo lag on our puny little 1.5L engines. What you feel is throttle programming. Our little turbos don't make enough boost to feel a kick in the pants. They're more like a CPAP machine for our 1.5's. 😂. For what it's worth, I'll take my 32mpg and little 1.5t all day long.