This weekend I bought a set of 206 RC (GTi 180 in the UK) calipers from a guy who has a rally car, but it runs already on 4 pot AP Racing brakes.
So I mounted them with Ferodo DS 3000 pads and drilled discs on my VTS. Even the 15 inch winter rally Speedlines fit this setup.
Well, completely different than standard road use brakes. When cold, completely no or just a minimal brake power. So I drive a few hundred meters with left foot on brake and gas. When it becomes warm, much better. When I brake agressive and suddenly, it stops the small car immediatelly. The only problem is the longer pedal way, probably I will need to mount a bigger master cylinder (206 RC or 406 V6 or something similar)