I've read on here numerous times after someone's spi inevitably drops a valve seat that swapping a zetec is cheaper and easier than getting another spi. I don't really understand that logic, I mean if you really want a Zetec by all means do it, but how is replacing your spi more expensive than having to get a Zetec engine, transmission, ecu, alternator, complete exhaust, etc. ? I'm not asking this to be a jerk, I'm just curious because when my spi eventually fails (which I hope won't be for a long time) I was thinking of just going with anther spi with a better head.
I'm not trying to be a dick but us guys that have had to deal with dropped valve seats in the SPI before, its a "common sense" thing among us that you arent really going to understand till it happens to you, thats why im assuming that no one has really taken the time to explain this to you.
Junkyards know how often the SPI blows up and they know they can make big money off of them when they get a wrecked Focus SPI in with a good motor. Its not like you are going to a junkyard to get an engine for Honda, engines that arent in demand so prices are fairly low. Any high failure rate part or engine on a car will be expensive at junkyards and at parts stores.
To answer your SPI to Zetec question...quite frankly the SPI is a joke when compared to the Zetec. The Zetec is smoother, more powerful, has a shitload of aftermarket support, very reliable (bulletproof is a better word), and i could keep going on and on. Zetecs are NOT in demand, every junkyard Focus I see that has a Zetec always has the engine there and it runs, the Zetec ones are always wrecked. Zetec = cheaper from junkyard. Swap? Not difficult compared to most other engine swaps. You only need a few extra parts like Zetec ECU, wire harness from ECU to fuel pump which takes like 30 mins to get out, and some other minor shit up in the engine bay i forget what exactly cuz i havent had a Focus since May.
I hope this answers your question.