To be fair, I've seen more than a couple of crazy builds north of 500hp on the 2.0 MZR. That 0.3L doesn't mean much when you're running a big turbo at 20psi (or whatever those crazy puerto ricans are running). It's certainly no obstacle to making massive amounts of power, in fact I seem to recall reading that the shorter stroke of the 2.0 takes to big power builds better than the 2.3.
But, on topic... Those ebay turbo kits are for two types of people: a) People who have enough junkyard fab skills to get it cobbled together, but no money; or b) people who have the money to blow on a turbo kit but not enough common sense to do it right.