The MRC shocks used on ALL sub-models of a given model (regular and v-sport and -V) are all identical. It is the programming that varies.
Actually, to clarify, the MRC shocks used on the 2013-2015 models ARE different than the 2016+. They had a few revisions since the MRC design used on the 2013+ models is different than the previous generation. They did a few revisions (three to be exact) and if you buy new MRC shocks, you get the newest version now a days. They are all backwards compatible.
The issue is not that they go "bad" prematurely. They ride great and last like any other shock. Some seals go bad early. I had both rear MRC shocks of mine leak by 40k miles. Both were replaced under warranty.
The issue with the early versions were that if you let the car sit for too long without driving, the shocks could end up acting like they got totally stiff.
Now, I have personally verified a "fix" for this issue on the early version shocks.
As it stands I have a number of other vehicles to drive, so my CTS4 Performance may end up sitting for 6 months over winter and it is not uncommon for it to sit for at least a month or two even during good driving weather depending on what else I have going on. Last spring I took the car out after sleeping all winter in the garage, drove it and noticed it felt like the front shocks are totally solid. Every bump was a bone-jarring experience. So much so that I was concerned about damaging something. But, the day I took it I had two other vehicles down for repairs and I had to drive it so I did.
I drove it for a week like that and it slowly got better. By the end of the week it rode just as nice as it always did prior. I drove it for another week and still no issues, perfect ride.
I checked the front struts, there were no leaks and nothing showing there was a problem.
So, I let the vehicle sit for a month (I had surgery so I really didn't drive too much anyways) and went for a drive... It was fine. I let it sit for almost three months because life was busy, and took it out and low and behold it was stiff and bone-jarring again. I decided to order new struts and resigned myself to putting them in. They arrived, but I was in no condition to take on a strut change, so I ordered up some tools to do it properly and resigned myself to doing it when I felt better.
Well another 5 months went by, I postulated what is going on (I believe the magnetic fluid stratifies inside the strut and as such needs to be "mixed" to make it react properly again) and since I got a set of QuickJacks I decided to test out my theory. I took the car out and it was bone jarring once more. So I drove back in the garage, setup the QuickJacks under it and lifted and lowered the car a good 6-7 times from resting on the ground to the suspension fully extended with the wheels in the air. After that I took it for another drive and low and behold, it was soft and supple again. It wasn't 100% perfect, it was about 70-80%, so I am hoping that the next time I go to take it out (I am doing a brake and engine upgrade) I will go up and down with the lifts about 11-12 times and hopefully it will mix properly and "fix" it.
Ultimately, I will swap in the new struts I purchased as that is the real fix. They are the third and latest revision and have the fixes done to the fluid (I was told they went through a couple of formulations and ended up just using the same fluid they used in the Corvette MRC shocks in the end). It sounded like the early couple of versions tried to utilize a different (ie, cheaper) version of the magnetic fluid, but in the end they just went with the same used in the Corvette shocks and have not had problems since. This was told to me by someone who works on the engineering side of these shocks, so I don't have any further details. All I know is the shocks from 2016+ are all "good". I guess they decided to fix things permanently because of the new model Camaro since it has the MRC option as well.
Also, as a FYI, MRC shocks are not like other shocks, they are a "lifetime shock" in that there are no valves, no actuators, nothing in them but a pressurized magnetic fluid that is kept in with seals. There is nothing to "go bad inside the shock.
So, in a nutshell, MRC shocks shouldn't go bad unless a seal leaks. As in EVER. The fluid on the early ones can stratify if it sits for too long. The fix is to work the shock from low to full extension to "mix" the fluid and allow it to operate as it should. The newer replacements have a different fluid that does not stratify.
Again, this is all based on my own vehicle and my own observations and discussions I have had with others, and have been validated through my own efforts. So YMMV.
