it isn't there for sound reduction. it's there to vary the exhaust pressure under different rider demands. exhaust pressure is important. don't disable it.
i so beg to differ
it has been proven time and time again on a dyno that this has nothing to do with performance.
with my own 600rr on a dyno there was no difference on a dyno of a run with the cables on or off
this has also been proven over and over again on the 1000rr as well
here are some articles for the uninformed
this site says that a good way to lose power is with backpressure
this site says you need the most exhaust velocity possible with backpressure as close as possible to zero
this one gives a formula that for every 1" hg of back pressure you have you lose 1hp
a little off topic but this site says exhaust valves are there to warm the cat on a cold engine
so many others but they all pretty much say the same thing.
in fact the only sites i found where they say that any backpressure is good is where the pipe is too large and allows the gas velocity to slow down, or just some guys opinion with no scientific evidence