+1.Scenic 1.616v!Rear caliper piston 34mm plus the bigger brake pad and the disc ~270mm!!Look into mk1 laguna/safrane rear brakes, supposedly you can fit the entire rear hub assembly including stub axles etc straight on as that's what the later Cup Racers ran, the benefit is a separate hub and disks which are bigger and so Re the caliper pistons.
The only thing I'm not sure on is if the handbrake cables fit, brake lines can be adjusted easily.