Well its been nearly a week with my new HKS style zorst fitted and all i can say is "wow" love it. If you are seroiusly looking at these exhausts, i wouldn't hesitate in getting one on your zed.
If you happen to stumble across one for sale, buy it.. honestly the sound is IMO amazing.
If you like sort of loud, not K1 loud then you will love this, and the look of the exhaust is to die for.
Really, i cant hype this up any more, it IS the dogs bollos'.
I have not noticed any performance gains or drops, just the sound is amazing and the looks, well.......