No way!... I have the GTHaus Axleback section (rear) as well, and then I added Berk HFCs and it sounds amazing! No where near as loud as that video posted with the full GTHaus system and LTHs. That's just insane. I will try to post a video of my setup, but I am telling you... I have the set-up and love the sound. I like it better than any exhaust system on a Z I've heard. Not too loud, but still has that exotic GTHaus sound, and a perfect tone to it. You won't be disappointed.
GTHaus Axleback + Berk HFCs =
