If you say so Mr. Complete Bunch of Crap. Just so you know, I did a pre header dyno, installed long tube headers on my SRT-6, did an open header dyno and finally a dyno with the stock resonator to muffler. 4 hp gain. Not a lot for the money. You can add up the cost. I did around 10 dyno pulls, the cost of the headers, expense of the install, retune. Perhaps a bit more could be found with a true dyno tune but even then you won't find much IMO. Almost all the gains I found in the exhaust were from removing the cats.
So be like me, don't believe it and do it yourself based on results from cars you've had in the past.

Les