Finally put a single outlet borla on. A bit disappointed in the sound as it is too quite for me. On the other hand, I've never had an exhaust on any of my cars turbo or not that I thought was loud enough. In any case, just as I suspected, the first muffler does most of the muffling. The axle-back looks pretty stock and sounds like the car should have sounded like from the factory. Almost silent at idle and some bark when accelerating.
I guess, that's fine. This is not the type of car someone my age would want to be screaming. Did loose some mpg. I would say at least 1mpg, but that may be due to the cooler weather we've been having. Or may be the stock system does provide additional back pressure for better fuel economy at the expense of some power. If that is the case, a full catback would see some gains. I am leaving it as a possibility.