alright im looking for a big brake set up for my mk2b 5 door 1.2 8v with intentions of putting a bigger lump in, whats the biggest fronts i can fit under 15's? and is there a rear disc beam that will fit?

cheers

Take the rear beam off an HGT for the rear brakes, that's easy enough, munkul has provided a guide. As for the front brakes, HGT calipers won't actually fit, since the hub carriers are different. However, Punto GT calipers fit, and will give you 257mm x 20mm vented discs. Try to get calipers from a GT3 since these have a larger pad surface area and are less prone to corrosion than GT1 calipers. Incidentally, I do have a pair of GT3 calipers available, but they could do with a strip-down, painting and rebuild.

Fronts: Bravo HGT may fit with a bit of work but if you get a set of 17s, using a custom mount you can get a set of 4 pot Brembos mated with Coupé 20vt 305mm discs in there. You will have to change the master cylinder for this though

Rears: As above, a Punto HGT has rears and is relatively a straight foreward swap. Although if your going custom, look for a set of rear calipers that take vented discs and use 257mm vented discs from a Marea.

This is what I'll be doing in the next few months altho I am building a track car....

Bracket for fronts:

If you fit an HGT rear beam you will also need the handbrake cable. If fitting a bigger lump you also need to consider the radiator. You may need the HGT rad cross-member.

Which lump transplant are you considering?