This forum probably ain't the place for this kind of thing... but hell, there's not a whole hell of a lot else going on!!
The SVX is a normally aspirated, H-6 engine producing 230Hp and 224lb/ft of torque.
There was no turbo version produced, but there are those out there who've successfully fitted a Garrett turbo to the car and got it to run, though only at lower psi's so far.
There's not a lot of aftermarket, but there's a good number of creative folks out there. There are aftermarket suspensions (though hard to get hold of), aftermarket exhausts, chips etc, even aftermarket tranny rebuilds (level 10)... but it's not as active as, say, the Mustang market.
I could go on for hours... suffice to say there's only 15,000 of them in the US... probably closer to 12,000 by now. It handles wonderful... so good that my '94 LSi is the second I've owned. There's a club at http://clubs.yahoo.com/clubs/subarusvx that has now seen over 50,000 messages to which I'm a frequent (and one of the first) contributor(s).
If you want to ask more questions, you can drop me an email at firstname.lastname@example.org any time... I'll be glad to answer any other questions you have. I am a true fanatic