It's true, sparked a giant debate and turned a lot of the members on FitFreak against AJR's products. I'm amazed it took this long to reach the other car forums.
I'm currently running one of these exhausts, back then when I purchased it I didn't check for a plaque, or any form of authentication, just took the shops word for it. It doesn't sounds bad or looks "fake" by any means, just a bit bland looking. But what the hey! AJR was reputable and trustworthy, so here! Take my Visa.
Besides that, I have nothing bad to say about AJR, their service is pretty up there and they are a friendly bunch, everything else I have ordered came in just fine and authentic. The suspension setup I'm on which is also J's racing is 100% real, which is why I find that the exhausts being the only J's products that were deemed fake a bit weird.
Buyer beware I guess, always check for authentication on the products you are goin gto spend your hard earned money on.