Actually bankshot, this whole idea of a muffler back pressure being a huge restriction of HP, or a big benefit to mileage, or reducing emissions, has not been proven and doesn't really make a lot of sense.
Surely, you jest. Do you think that Vortex Exhaust Technology has all these dealers selling a product that "has not been proven and doesn't really make a lot of sense"? Take it up with Vortex Exhaust, then, here are all their dealer addresses:
Or, take it up with all those that have tried the product(s) and have written these articles, below, such as the one in Car Mechanics Magazine and Total BMW Magazine. I'm a little surprised at you, your...post...that doesn't really make a lot of sense. Perhaps read through their site a little. And, no, I didn't create their site and I seriously doubt that GRBT did, though, that would have been an extensive undertaking, if done, and...potentially very exciting for shareholders, lol...
Actually, I'm hoping that GRBT's licensee's first application for the EVT {Encapsulated Vortex Technology} is not automobile related. Hoping for something more...unique, obscure...exotic. Unless, of course, the first licensee happened to be Vortex Exhaust Technology, themselves.