Welcome to the club!
First of all, bodykit, depending on where you are you should be able to pick up a VS bodykit for about $16-1800. Thats for a fibreglass copy of course and remember that thats only the kit, unpainted! Remember that fibreglass kits don't usually fit perfectly so you will have to get a panel beater to fit it for you, add to that painting and you get the idea of the $$$'s you'll need to spend! Bare in mind that your front bar will inevitably get scraped along a driveway or road at sometime and possibly cracked as fibreglass is not the most flexible material in the world
Rims, 18 inch rims will fit but if you are planning to lower your car and add a VS front bumper be aware that you will need very low profile tyes, you will probably get some inner gaurd rubbing still though!
CAI, i've heard some good things from the CAI kit designed by steve and UAS, but it really depneds on how much performance you are after and in what rev range! I will say that if you are planing on fitting an after marktet pod filter then try and get an enclosed heat shield with snorkel pipe otherwise you will just be sucking in hot air from your engine bay, remember you want the coldest air possible into your engine!!!
Exhaust, i take it this will be for both wank and performance factor, remember that the stock FTO exhaust is already 2.25 inch! Just adding a better flowing muffler can give you quite good gains as well as a nice loud exhaust note, if you still wanted a 2.5 inch there are plenty of avenues you could go, i wouldn't bother with a hi-flow CAT though to me it seems a little unnecessary
Suspension, If you are going to go whiteline then get their suspension kit, have a look on thier website i think it's on there, i can't remember if it includes sway bars or not but i would
HIGHLY reccomend you invest in a front strut and sway bar, they will make you handling improve out of site
Oh and don't get coilovers IMO they are best left to the track not the street.
As far as painting your bodykit goes, it depends on what paint they are using. If you are staying the stock black colour they shouldn't have any troubles painting it, just find yourself a reputable panel beater in your area (sorry don't know where your'e from)
Extra power is hard to calcuate especially depending on where you will be achieving it, i'd assume with a good intake and exhaust setup you could gain anywhere from 10-15kW but again that doesnt mean that the car will be a lot quicker from the get go, think hard about where you want the power and mod accordingly
As for 0-100 times id say low 7's possibly high 6's if you have a well tuned GPX (or a freak GR) there are exceptions to this but they seem to be only a few! Quarter mile times range from mid to high 15's to high 14's but id say you would be looking at about mid to low 15's if your car is setup properly after the modifications, remember things like bodykit and biger wheels add weight though, so it depends on what you are after
Damn that was one long post, hope this helps a little and if i have said anything wrong someone else will correct me
