Header wrap only promotes corrosion if it gets wet all the time. I wrapped a header for a '91 Civic and the header didnt have ANY rust after two years. It also stays alot drier here in CA.
The header was out of the car and I cut strips longer than I thought I needed. Then I secured them with hose clamps. I only wrapped the header because the A/C lines came really close to it. I wouldn't do it for fun.