I'm not that knowledgeable with regards tuning (prefer driving stock, anyway), but I often alter brake balance. My "rule" is pretty simple (too simple, I suspect): on all cars I use Front 5 / Rear 3; and if the car's got a racing brake kit, I use 3/1 as that seems to leave a bit of travel in the brake pedal before lock up. I use ABS=0. I'd be very grateful for other users' views on this as I think I may be oversimplifying - I make no changes relevant to whether cars are MR, FR etc. And I ignore front/rear weight distribution.