Nobody is refuting that those are at least decent numbers. Let's not get into dyno politics in this thread.
I think the sticking point for many of us is that we fail to see a $6K stainless steel exhaust system selling very well. That's basically around 20% the value of the car, why would you do that? I get poked every so often for buying an expensive exhaust, but at least Amuse gave me a pretty and stupidly light titanium (if somewhat ill-fitting) exhaust for it