Could someone tell me the differences between the ej22 gen 1 engine and the ej22 gen 2? I know the engine loom and manifold are different but what are the improvements fron gen 1 to gen 2? Does the gen 2 engine have more hp or better fuel economy ect ect?

The oil control rings changed in early gen1 engines but aside from that there were no real changes till late 90s EJ22s to the actual engine itself, it was all the bolt on crap that changed, the new heads on 97 onwards are interference though so if the timing belt jumps or breaks you got bent valves.

The Gen2 actually make less power with Australian models, not enough to notice though.
It was mainly the exhaust system, dropped power but raised torque.

90-94 gen 1 EJ22M 100kw/189Nm @6000rpm
95-96 gen 2 EJ22E 94kw/190Nm @ 4400rpm
97-98 gen 2 EJ22_ 98kw/193Nm @ 4400rpm

Thanks Joel, I didn't think there was anything major. I have a Gen 1 in my Baja and a mate is about to go Gen 2 in his buggy and noticed the different shape manifold and engine loom (interchangeable I'm told).

Its mainly just a few sensors that need swapping (knock,cam and crank) to make the engine match up with the loom.
rest is all in the manifold which can be swapped.