Cheers Mike, and welcome to the club.
You'll find that the site is fairly USDM focused, and my understanding is you guys have some major differences in product availability ($) and tuning options.
That being said, over hear $20K would be easily in the 11's. I'd recommend doing an STi transmission and the 2.5l.
Here is a good explanation on the traditional hybrid:
EJ25 Engine Installation Guide
I thought I had read someone was doing it now without using the WRX intake manifold by attaching the cable throttle mechanism or something though. Also I thought there are considerations regarding compression that don't seem to be covered there.
I'd talk to the tuner who is actually going to tune the car about the compression and the rest of the setup - injectors, turbo choice, etc.