Brake Query

Hey all. I have a N15 Pulsar(Almera GTi) and I'm trying to work out a decent brake upgrade.

I was thinking of 200sx calipers and I did a bit or research and I came across that the ZX calipers are alloy and so should be lighter. What I'm looking for here is a bit of info. Whats the difference in calipers on the ZX? I was told theres at least 2 types. If so are they all alloy or are some cast? Is there any other differences? What distance is between mounting holes on the calipers?

Also what are the specs on the standard discs? eg diameter, width etc.

Any other info you can give will be greatly appreciated!

Thanks in advance.