1. Where have you been searching that says the cold air intake adds 20 hp and the exhaust adds 15? Those 2 mods at the max might give you 5 more hp.
2. Most aftermarket pcms will kick the fans on at 185ish instead of the stock 213* and they also keep the fans on after the car is shut off, that is the easiest way I can think of.
3. I wouldn't run anything less than 91, especially if you are unsure of what mods have been done to the car.
4. Do you have any humming or any weird noises in the sound system?
5. You can use whatever oil you want. There is a few threads talking about oil search and read them.
6. Firestone or Bridgestones. Stay away from Goodyears.
7. Don't jam on the gas, practice easing into the gas then going wot till you get a feel for what works best for you.
8. Yes as long as they are out of a 04+ gp they will bolt right in.
9. Again search the forums or google or youtube tons of info on doing this.
10. Probably not should probably take less than 30 min
11. I haven't no, but from what everyone else that has done it says they make a world of difference, and it looks pretty easy to do.
12. These are a lot of inexpensive mods that can be done search the forums, look at others rides, read stickies, there is one for mods that cost less than $50.