the jumper mod disables a flapper valve in the exhaust. it makes the bike a bit louder but it allows it to breathe better. And yeah - it works on the new ZX6s - ie the real 600cc bikes not the fake ones.
Adding the jumper causes the ECU to disable the flapper valve and switch to the euro spec maps for fuel and timing. The net result is like 5hp. when I was looking at buying an 08 ZX6 this was at the top of my list for To-do's. Probably would have done it as soon as I got the bike in my garage.
As it it....I got something a bit bigger that doesnt require a jumper mod for an extra 5hp. But it isnt a real 600cc bike either.