I take it you don't believe me then!!!
No too much really. You'd be suprised how easy it is to get 340 bhp.
New ECU, which increases the boost. would take the car to 300 bhp alone.
Then I changed the up pipe and the down pipe, removed both the catalytic convertors and replaced with sports cats. Changed the back box, and the breathing unit. Replaced various piping in the engine bay to cope with the extra power. Changed the Intercooler for a larger one and added water spray. Then I got a slightly bigger turbo, but not too big, so it still starts spining up early, at about 2000 revs. A new fuel pump was also needed at this stage. Then I needed to think about safety so I added a DECs unit and a knocklink, so I can check on boost levels and oil temps, power ratings. etc. But in all I only spent about 6,000 US dollars, or £3k.
I was gonna buy a 2.5 US Sti engine and work on that, to get about 600BHP, but it'd cost a few thousand, and it'd be wasted money. So I'll probably buy a different car, not sure what yet. I want an old American classic, but I'm looking for a good importer.