On other zs I've owned I've had both. I always end up ditchen the hks because of its ricey look and not being loud enough. B&b both looks and sounds better. How ever I'm sure hks flows better. Also hks is a big fan of getting exhaust tickets here in va.
2006 Chevy Cobalt SS super charged (Daily driver/Gas saver) 1994 Nissan 300zx sport 700 Twin Turbo (Weekend car)