If your making 400 HP at the wheels now and are going to pump up to more power later, I'd bite that bullet and get the TTi headers (assuming your going for at least a 100 HP increase at the wheels). The coated headers (either Doug's or TTi) act as a thermal barrier (which is a good thing) in this aspect TTi is better because they also coat inside the tubes (extra coat which works out to be $750 i think for for the headers total) which smooths out the tube which equals better flow. The step headers are as big as it gets unless you want to jump up to fender wells.
