I think the first question you need to ask yourself is: why did you buy the car???
drag racing? circuit racing? show car? dyno queen? daily driver with a little bit of poke?
in what way do you want it to "go faster"?? straight line? round a circuit?? top speed??
then do mods to suit your purpose
you're modification path will be VERY different for different purposes. The first thing I think you should spend your money on is yourself.. get out on the track or drag strip or skid pan and learn to drive your car to it's potential, learn to drive it as fast as it'll go. To give you an example, 2 different people I know did the 1/4 mile in the EXACT SAME CAR and did times 2 seconds apart. Now if that doesn't open your eyes to how important the driver is then nothign will.
I wouldn't mod my car just for the sake of it.... what a waste of money!