I have read through both links.
While I don't think that the MRT exhaust owner was telling a lie, it is certainly obvious that he was pissed off that his exhaust was rusted after three years and that he had to pay to get it off his car and to replace it.
But does that mean that a MRT exhaust should not be purchased? In my mind, the fact that no other bulletin board members posted that they experienced a similar problem shows that this was an isolated incident. Also, the fact that this irate former MRT exhaust owner did not contact MRT to fix the problem, but instead decided to bitch (with multiple CAPS LOCK posts) on their own bulletin board shows that while he is pissed and irate, he did not do his due dilligence and at least contact MRT.
I understand the owner's reluctance: Too often we realize that our complaints get unheeded, especially when dealing with a large corporation. But MRT is not a large company. The MRT's owner personally responded to this person's complaint. The MRT folks seem eager to at least investigate and, if they had given a chance, may have rectify this problem. That speaks well about their character and customer service.
Sure the owner has already fixed the problem and doesn't have time to drive down to MRT. But does that mean he can go off and flame away at MRT? In a sense yes, but the only point that that proves is that one of the MRT exhausts was rusted through after three years of usage.
Does this all stop me from buying a MRT exhaust? Absolutely not. I prefer a smaller company that cares about the problems of their customers and I understand that sometimes a product may have undetectable manufacturing flaws or may wear prematurely.
Now if more people posted in stating that they had a similar problem or if the original poster showed that he contacted MRT and they ignored him, then I think he'd have a more compelling argument to not buy MRT.