Re Jetting Mikuni BS34s

Hi
My trusty old 4 into 1 motad exhaust has reached the end of the line and its time to change to a new exhaust. I have a local metal fabricator who makes exhausts as a sideline, who will make me a Stainless 4 into one for the Z. He was showing me a megaphone style silencer also in stainless but it has practically no baffeling inside it. The silencer is pretty small and Im thinking of using it I might be able to get the guy to fit somewhere to attach a baffle at a later stage.
Anyway have any of you had to rejet a set of carbs to suite a new exhaust? and what advice can you give me?

Thanks guys!

If your carbs had already been jetted and it ran good on the old 4 into 1 then I would say they will be fine.