Just to add, changing just pads is perfectly fine, provided the disks are in good shape i.e. no scouring, have a flat face, are not warped and are above the minimum thickness.
I've fitted Red Dot six groove disks & fast road pads. they have lasted 20,000 miles & the disks are still in excellent shape. new pads are required though. Not bad for a car that has been used regularly on track, & not so hard on the road...Honest!!!
Braking with these was a big increase over the standard pads & disks, which weren't too bad themselves.
When fitting new brakes, always clean the new pads & disks with brake cleaner, to remove the protect oil's used. re grease the sliding pins & make sure to bleed your brakes properly, new pads without new fluid is pointless. Used good quality Dot4 fluid.
Bed in the pads & disks gently over at least 500 miles, try not to generate too much heat. If you then gradually increase how hard you use them they will work beutifully. It's like cooking a chicken, Slow & long is better than fast & hard.
I had a problem with a squeeell
which I cured by adding an anti-squeal pad on to the back of the pad. Sorted.
I was only going to do a quick reply