Which Bolt-ons are best for a 99+ GT?

[red82gt]

This is for my friend's car. He wants to start with a shifter but doesn't know what to do next. If you could, make a list of top priorities for bolt-ons. Neither him nor I have the facilities to do anything major so nothing too heavy duty, he's looking for a very low 13 second car. These are what we're considering:
1. Cat back exhaust (entirely for the sound)
2. Catalytic X or H-pipe (emissions is an issue)
3. Gears (373's or 410'S?)
4. Pulleys
5. Cold Air
6. Headers?
7. Mass-air meter
8. Sticky Tires.
How do these sound? Any suggestions for name brands? What are we missing or what should we drop?
Thank you.