Right chaps I've decided before taking the big plunge I'm gonna try to refine my current 1.6. My clutch is slipping so that is making a big difference to performance. These are my plans:

Skim flywheel
New quality clutch
4 branch manifold
Twin Weber Carbs

Clutch aside do you reckon this should make a noticeable difference?

Also in regards to the Weber carbs does it make a huge difference if they're second hand and should I be running 40's or 45's. Also what's best place to look for them..? Ta