I see this question a lot from new forum members that have just acquired an mx6 and have started reading on the forums a bit. The following pics will show the difference between the engines so you can identify the engine sitting in your engine bay.
KL03 (or KLDE as it is also known) :
Chances are, this is the engine sitting in your engine bay if you have an LS model mx6 (or GT Ford Probe) here in the US. This is a 2.5L V6 engine, and it has roughly 164 hp.
This is the japanese spec (JSPEC) engine that came in the mx6 in Japan. The KLZE is more or less a direct swap for US cars equipped with the KL03/KLDE and produces around 200 hp. A swap into a US 4 cylinder car is significantly more involved, though it has been done. Go here
to learn more than you ever wanted to know about this engine.
FS01 (or FSDE)
(Excuse the crappy picture of my own old car.
This is the stock 4 cylinder engine that came in "base" mx6's, the RS model. It makes around 118 hp and is decently good on gas. Can be turbocharged, but that's a subject for another thread.
You don't have this motor. Trust me.
This engine was available on the japanese spec mx6 base. Notice that instead of a distributor, it has a coil pack near the oil cap. Also notice the large black chamber on the intake manifold for the VICS chambers (similar to the VRIS system on the KLZE and KL03.). Before you ask, NO, you cannot easily swap one of these engines into a US car
. The engine is completely different electrically. You would have to modify the original jspec wiring harness and use the jspec computer or you would have to build a custom harness and put an aftermarket standalone engine management system (such as Megasquirt). Due to the complexities, and the limited power advantage over the american FS01, almost no one has bothered to do this swap.
I hope this quickly helps answer a common question. Now that you know what engine you have, you can direct your searches on the site to the particular enigne in your car.