I've chosen to go with the custom DIY braided lines.
What size banjo fittings fit the r32 gtst 4 pot calipers ?
Also how long are the brake lines on the u12 ? 1200mm ?
I hope by "DIY" you mean that you are getting someone ELSE to make them up for you.
You CANNOT make your own flexible brake lines unless you have the correct hydraulic crimping machine and tooling to securely crimp the fittings to the hose. Using compression fittings that can be disassembled are NOT ADR compliant and are just plain dangerous for brake systems.
Nearly any brake workshop will have the gear to crimp the fittings to the hose, and can make up ADR approved braided brake lines.
From memory I paid about $100 to have the pair made up for my black U12.
Take the caliper and an old front rubber brake hose with you, and a brake workshop will make them the correct length with the correct fittings.
For your reference, R32 4 piston calipers do not use a banjo fitting, they use a female tube flare and male tube nut (M10 x 1mm) to connect the flexible hose to the caliper. Remind me and i'll take a pic of mine tonight.
Also ensure that the the braided line that is supplied has the extruded rubber / urethane cover over it. Most places typically supply them in clear, so you can still see the braid, the place that did mine had choices of colour tint for the extruded cover, I had mine done in black. You can just see the braid through it.
While you are at it, take your flexible clutch line down and get it made up in the same braided line with fittings to suit.
Sounds as though you have the same calipers as me, 30mm alloy 4 piston. My rotors were also bought as blanks and drilled to 4 x 114.3, I also had the same brake workshop that made my braided lines turn the rotors down from 280mm to 274mm.
When I replace the rotors after the next couple of track days, I'll be going straight to a 300mm rotor from the R32 GTR and machining up an adaptor to move the caliper out from the hub to fit the rotor. I think it will leave me with about 5mm clearance from caliper to wheel with my 15" Weds...IIRC.