You wont see any performance gains with a different zorst. You would need to have the uprev done once you have the zorst fitted.
The ecu tunes itself when it sees something different attached. So you will have the noise but very little gains.
I assume that thee will be some sort of muffler somewhere on the zorst? else it will be fooking loud.
How much you being charged btw, have you looked at buying a miltek zorst, may be somewhere what you are going to pay and less agro.
You should get to some meets before commiting to something you may regret, loads of us have aftermarket zorsts fitted and this would give you an idea of noise levels.