I found that the best baffles for the JapSpeed K1 involve mechanical and permanent exhaust modification.
First jack the car up so you gain access to underneath the Zed.
Once secured, remove the endcan sections.
Then move on to the mid section and detach from the y-pipe.
Now comes the important bit.
With the midsection and endcans removed, you can now set about fitting any exhaust you like, Scorpion, Cobra, Milltek, etc.