The 2.3 showed up in certain "green" states and border states in '03, a PZEV engine. In '04 it was more widely used, and in '05 the 2.0 Duratec was standard with the 2.3 only in the sedan STI version.
The Duratec 2.3 has approx 144 hp stock and is superior to the ZETEC. IIRC the 2.3 has more hp than the FSVT, a little less tq. The 2.3 can be a mid 15 second runner with just a few bolt-on/deletion mods. There are also a couple 13 second N/A 2.3 duratecs, they are heavily modded. Cosworth has a slew of aftermarket parts available for this engine, and there are at least three companies making headers. When a F/I system is developed for this engine it will be a rocket.
There was a discussion about this a while back, the 2.3 was used in the Ranger and I think Big Jim stated it was actually a Mazda design. A variant of this engine is installed in both the Mazda 3 and 6, both with higher hp numbers than the Focus.
