I havent dealt with them long enough to say "yank em out now" but I believe that there are better options out there.
I dont care for mine because of the high arc on the driver side. It throws out lots of heat near the top of the engine. In my limited experience, it cooks the brake master clylinder and anything else within close prox (ie. valve cover, upper intake, wiring loom).
If you do take them out, you've got a bit of undoing to do. The KB headers move the turbo up and forward so (if yours is like mine) the oil, coolant and intake piping has been altered to accomodate it. Not gonna be an afternoon job in the garage. Check it out closely before you dive into it.
I dont know how those headers compare to stock. Have seen some setups that still use the stockers.
Are you using the KB air to air cooler as well?