For which one?
I would take some advice off Kev @ Envy or another tuner esp if your going for TT. I understand that TT changes the engine not considerably so what you have now may jot be what you end up with...
I paid £700 odd for my 5zigen, am well happy with the noise and what it does so in my mind that would be still £700 odd from you zorst and then £1200 to spend on other toys like suspension, flywheel, clutch plate, suspension, etc etc that you will need to spend if your doing a TT.....