I've been following the STI detonation issue on the message boards.. this thread in particular has some good info in it by some of the big name tuners. It's looking like something with the factory fuel enrichment mapping... or something... heh. It's particularly bad with the CA 91 Octane shite.

Anyhow... i got to sit in and inspect one yesterday at lunch (a buddy here at work's roomate picked it up yesterday). The tires and brakes are intimidating on their own... it's pretty bad ass. The painful part is that the guy who bought it doesn't even know how to drive stick... this is his first manual car. Oh the pain. Hopefully i'll get a test drive once he breaks it in.

another interesting thread on the topic here.