Look at it this way.
You are a Service Advisor. I come to you with a car with an aftermarket exhaust pouring out smoke. You tell me to put the stock exhaust back on. I do so, the smoke goes away.
Now I say, but the cats are just hiding it, and a bunch of people on the internet say there is a problem.
Thats when you, as a Service Advisor, tell me that there is no TSB and no Recall. I had an aftermarket modification to the exhaust, and upon replacing it to stock, the smoking went away. Therefore, it was my modification that caused the problem, and not the car.
OR
I pull out documentation (and I am that asshole who carries that s*** with me everywhere) to show that a number of Speed3s have had the smoke issue on the stock exhausts, and that the problem lays in the turbo seal. I have documentation that shows the fix is a turbo replacement. And before they say that I have an aftermarket exhaust so sorry 'bout your bad luck chief, I pull out the documentation that dealerships have been fixing the seal on cars with aftermarket exhausts. They now have no ground to not replace the seal under warenty.
I'm not gonna waste time on this one.
I'm not in anyway saying there isn't a problem. I can pretty much say that short of turbos shreading and sending chunks of metal through the engine bay at rather high velocities, there will not be a recall on it. However, you can damned well expect that showing up at a dealership with a faulty seal and smoke pouring out the back of your car with an aftermarket exhaust, your solution is going to be put the stock exhaust back on. When you put it on and they don't duplicate the problem, the dealership is done. And telling your SA that "a bunch of people on a website have had this problem" isn't going to work.
This is why we need actual documentation available on this site and "the dreaded other site of d00m and despair" so that if you do have this problem with the faulty turbo seal, you can have something in your pocket when the dealership gives you push back.