Currently have standard M16 2pot calipers.

Would lightweight 4pots make a difference/improve braking?

4 pots should improve it as would green stuff pads or grooved discs

Mintex 1144 pads......that will improve things no end. Not a fan of greenstuff, no improvement over cheapo pads when I tried them. Now, the really old asbestos pads (sadly not sold for many years, but do turn up as old stock sometimes) are ACE but usual caveat.

On a light car the brakes are not really stressed. So yeas, a change will improve things, but unless you are experiencing problems, I wouldn't bother. Spend the money elsewhere where you will get a better return.

Another vote for keep the calipers, fit mintex 1144, avoid greenstuff on a seven like the plague.
I have just changed from greenstuff to mintex and it has transformed the braking on mine.

[Edited on 17/7/10 by Dusty]

Another vote for Mintex 1144 , they give a massive improvement with standard m16 calipers.

As above also make 100% sure the caliper pistons are moving freely and the pads can slide freely in the caliper.

If you want the brake pedal to be more responsive fit a smaller bore master cylinder --- from a non-servo Mk1 Fiesta or non-servo Mk1 Polo/Golf or the Fiat12/Lada master cylinder.

[Edited on 19/7/10 by britishtrident]

I went from Sierra brakes to Wilwood and only after fitting some Mintex pads did the braking actually noticeably inmprove. The lighter calipers, hub and uprights I fitted benefitted the handling more.