M coupe/Z3 engine weights vs. M3 engine weight?

[96cali]

I can vaguely remember a post here (maybe by J!m) explaining the different HP and weight varieties between the 3.0L Z engine, the 3.2 M Coupe/roadster engine and the M3 engine. Anyone know their stuff and want to impress us?

Is the M coupe engine lighter as I remember? Why? I am musing lately about an engine swap and cannot recall someone swapping in a coupe engine. And then I wonder why seeing as how it is lighter (if I recall correctly).

Here is a good rundown of HP per make of Z/M http://www.z3roadster.com/