these things were a handful in stock form, modified they are an animal. Can't remember if they came stock with an LSD - if not that should be the mandatory first mod rather than more power!
The asking is a little dear, but this at least was modified well within reason with basic bolt-ons that were not hacked together from Home Depot supplies. I would say look at similar hot hatches of that vintage, and adjust offers accordingly.
These also rust badly, as with all Mazdas. I don't think they ever fixed the rust issue in the 3s, but I could stand corrected.
I dunno why anyone goes for top-mount intercoolers anymore other than "hood scoops look cool" because a good front-mount is way, way better for performance and packaging. My modified R53 suffered from this, to go bigger with the intercooler after dropping to a 17% pulley it would have needed a lot of work.
