How much difference in power gains could one expect to see from the Mazdaspeed exhaust(axle-back) and a cat back exhaust like the bosal system?

Why does'nt mazda do a dyno when they release a so called "performance" exhaust like this?

Would'nt it be possible to use the mazdaspeed muffler and have a shop custom make it into a cat-back system to provide better flow?

Any thoughts from those with knowledge on the matter.........?

 

YES you could...for all the muffler shop needs to do is make you a replacement pipe that will go from the cats back to the new muffler and bolt up....all your doing here is removing the resonator.