If im honest i didnt notice any difference in fitting rear discs with regards braking performance....

i purchased the kit from Fiesta centre.... comes with everything bar the 2wd cossie calipers which i got from Ford.

The main reason I did this is once fitted on the car it widens the rear track

also the added benefit of looking nicer...

With race spec pads up front and standard cossie mintex in the back if the brakes are not warmed up the rear will lock... once warmed though stops immediatly with no locking .... no need for a bias valve.

For an every day road car i would recommend some standard compound pads and then change for track use