Since Pacesetter isn't going to be producing any Nissan headers for at least another month, the headers I ordered in January are not going to come anytime soon. Thus, I cancelled my order and now have some funds free to a different mod. What should I do next?

CAI for sure!!!!!

ive got well bleed brakes and some OEM pads and wow my car stops on a dime with a very firm pedal. Ask dennis, he will tell you. The CAI will be a much better "first" mod. Figure the brakelines for some time on down the road.

Im the exact oppsite. Brake lines. Why? Because being able to stop or modulate your brakes more important than a loud intake. Being able to rely on your brakes makes the car much nicer to drive. Plus being able to out brake someone wins races as well. Id also think about doing the ad22vf upgrade while you are at it. Cheap and worth it just for the fact you wont warp rotors as easily