Not to belabor the point, but CorkSport isn't that kind of company. I've had three after-market exhausts on this car alone (and many more on others), and this CorkSport one is among the highest quality of all of them (far better than the Simota I had, and better than the F2 cold air intake that was the first). To demonstrate my point that CorkSport is not your run-of-the mill aftermarket parts shop, let me relate my story in purchasing my Quaife ATB differential for my Mazda3.
I believe that I was the very first non-racing Mazda3 owner to install the Quaife. I had originally planned to turbo-charge my Mazda3, and as part of the prep for that, I did some transmission work. One of the things I wanted was the Qauife. I had a supercharged 2001 Focus ZX3 making 200 lb-ft. of torque, and the lack of an LSD was a weak point. Back in the first half of 2006 I found that the Quaife for the Mazda3 was the same as the Protege part. However, there seemed to be issues getting a properly warrantied Quaife at that time. Mazdaspeed seemed to be the only authorized seller. I think I saw it on CorkSport's website, and was wondering if it was OK to buy it there, but I can't remember for sure. What I do remember is that I called Mazdaspeed about it. I was told that CorkSport was the one-and-only legit place to get the Quaife for the Mazda3/Protege (at least at that time) if you were not taking your Mazda3 racing. The guy on the phone told me that CorkSport was Mazdaspeed's way of allowing street-driven Mazda3s the chance to have the Quaife.
I'm not 100% sure if I have all the details of that sory completely correct, but the gist is right. I know that MazdaSpeed informed me that if I wanted a properly warrantied Quaife, I had to buy it from CorkSport. Now, if CorkSport were the kind of shop to just throw together a filter and a tube and call it good, would Mazdaspeed have chosen them to be the one place to sell the Quaife to "normal" Mazda3 and Protege drivers? Probably not.
Also, I think I saw in the other thread about this product that CorkSport does have typical gains listed for the intake. With how common it is for aftermarket vendors to issue fudged dynos, I think this is just as meaningful.