The weight really isn't the cause to disconnect it. When you launch, the sway bar doesn't let your front end torque and lift the wheels as much(less weight transfer). Most people believe your 60' times improve if you disconnect it, and you maybe get a little more if you remove it.
i took mine off last time i went to the track. it didn't get my 60's any faster, but it did make them a lot more consistant there just wasn't much i could do on worn out tires
as for the weight thing, i still haven't put mine on, so give me a few minutes & i'll go weigh it...........