I'll repeat a rear brake story I've told a few times - bear in mind that I've always run bog-standard cheapie rear discs, with Textar pads
After fitting some new front pads, I didn't secure the ABS cable properly, and it flapped about and eventually got caught around the driveshaft and got ripped off - result = no ABS
As the brakes still worked fine, I carried on driving it while I sourced a new sensor and cable and got it booked in at Motormech.
A couple of days later, on my daily commute, I spotted a puff of oil smoke in the rear view mirror when decelerating - I put this down to a tired turbo - it only ever happened when the engine was decelerating hard - ie when I was reducing the engine speed on the brakes, rather than a natural deceleration. I thought nothing more of it, other than to work out how to persuade Wifey that I needed a new turbo
A few more days passed, and I spotted the oil smoke in the mirrors a couple more times. Then, one evening, I left work late and the roads were really quiet, so I decided to "make good progress"
So - down my usual commute route of twisty B roads, I started to edge the speed up, and as usual, I noticed the puff of oil smoke in my rear view mirror - nothing unusual there, but as I howled down a particularly nice straight and into a series of sweepers, I jumped on the brakes and very nearly put the car into the hedge, accompanied by a huge cloud of smoke behind me
It turned out that the 'oil smoke' was in fact tyre smoke from one of the rear wheels locking up on moderate braking. When I eventually got a chance to give the car a bit of a blast, the first time I hit the brakes hard, BOTH rear wheels locked up and sent me VERY sideways
So - the point of this rambling is that the standard Coupe rear brakes are more than capable of performing to the limit of the tyres - you have to remember that the standard weight distribution is 2/3 - 1/3 to the front, and this is even more pronounced under heavy braking - quite simply, there's probably less than a quarter of a ton on the rear wheels when you're hard on the brakes, so the rear brakes have very little work to do, other than keeping the car in a straight line
So - all you need is a correctly adjusted compensator valve and you'll be fine