i really am confused as to how 312's wont make it stop any better than the 288's given that the pad will be further away from the center therefor giving it more leverage is it not simple physics or im a completely stupid?
The difference in diameter makes very little difference in the real world, since the pads are the same, so the swept area of the disc is the same.
What you do get, is more metal to sink heat into...so they should go longer before overheating and fading.
But on the road, you'd be hard pushed to tell the difference between 288s and 312s.
280s to 312s...yes, as the 280s are noticably thinner (20mm vs 25mm) and have a significantly smaller pad area.
The diameter really doesn't significantly improve the braking...it just maintains it longer.