Well, late to the party here. First, that akra video is the best ive heard. Especially at 50 seconds in. I love the presence. However, I'd be concerned about the in cabin experience. Without the highs, I'd be afraid of missing the adrenalin rushing scream and howl that goes with 6k and above. Even my AA axle back screams, but not like the oem or even better the m performance. Yep, I said it, that weak oem screams, but it isn't loud enough because you have to go all out to experience it. I hope the Akra doesn't get boring to fast.
Finally, the next time I shop for an exhaust, it will be for my in cabin experience. Hell, the only time I piss excitedly in my pants from my AA is when my wife drives it. Then i hear the beauty of it. Other than that I have to use my imagination.