it will help, wether it is an auto or 5-speed. it opens up the tb and lets more air through with less restriction. if you look inside the tb all of those fins restrict and the sort of oval opening above the butterfly does also. i noticed a big difference, but mine is a 5-speed.
I wouldn't be so quick to do this. I did it a few months ago, followed detailed instructions to a tee and didn't alter the area around the butterfly one bit. Now my car has a bad stumble at lower rpm's during light throttle applications, say cruising at 35 mph in 5th. I'm not 100% sure that the tb is the problem, but I have no other mods that could cause this. Just a warning I guess.