ST170 discs, MK3 Mondeo calipers and drill your hubs out to 12mm, cheap and effective upgrade. Min 15" wheels required (don't quote me on this, but by shaving the caliper I believe they can be squeezed under 14" wheels!)

Fitting four pots like the Porsche calipers is probably possible but would need quite a bit of fab work, prob not worth it tbh.