including ecu, quite a bit - examples;
exhaust may be $600-1k
intake - fark that, leave it as stock box but change filter to something decent. $100
boost - go with an electronic boost controller, can probably get one for $300 or so
ECU - anywhere from 1-2k for ECU, then tuning time.
all in all, not cheap.
I've got a 33 gtst with exhaust, new panel filter and boost controller on 10psi and i'm running 190rwkw at full song, albeit with massive rich and retard in the middle (goes nuts once it's past that though). installing SAFC to smooth that out.
By no means is it the quickest car out there, but for the road, it's more than enough - you wanna stay on the good side of the law.