with a turbo you are looking at some major power. but it's also going to cost you in the realm of reliability.

if you are going to have this car for the next 5 years i would take it slow and start building it NA

with about 1500 you can increase the power of the car substantially and i feel be pleased with the results. not only will this NA build be cheaper but it won't result in many other costly repairs or added goodies.

if you wanted turbo i can imagine you pushing nearly 300 horse on a stock type-s, it's alot but it will cost you more than just putting the kit together to run turbo. tuning costs, LSD-- all that fun stuff.

:edit:

my friend previously had an RSX type-s before owning his STi--

with bolt-ons and a hondata reflash he was in the 13's without sacrificing anything. i'll admit you'll be faster with a turbo, but thats not the only thing to look at here for a DD that is only 5 years old.