Nice gains! Thanks for posting up your dyno. We took extra design considerations knowing that many of you will run Berk HFC's with our exhaust. All of the videos you have seen of our cat back have Berk HFC's installed. It's easy to make an exhaust sound great with the OEM cats, not so easy to do it with HFC's at the same time.
Mike @ Doubledown motorsports has put several thousand miles on his system with HFC's installed. You can hear the inside & outside sound clips here:
YouTube - Berk Cat-Back 370Z Exhaust Exterior Sound Clips
YouTube - Berk Technology Cat-Back Exhaust In-Car Video