Yeah I've been there done that. I could have done it cheaper but - it was time and Engineering problems.
In fact it was fairly expensive. As I had some 4 spots which turned out to be too much ot fit and well I would of been stuck with 300mm rotors not the big ass ones I have now which I think are about 330mm or so. As for rear brakes, all power is always at the front. Bias control - Just remember that's illigal in cabin and adjustable, on street.
Plus only if your using it for curcit.
If I had the time I would of done it like a friend AP racing calipers.
Factory brakes are GOOD - In fact Excellent on n/A's and light model Mx-6's on a heaveir and 4WS/ Auto models they don't hold up as well.
Corrvette C57 calipers with discs do the job in fact it's the discs nothing else really.
4 spots would allow a bit more pedal feel, yet woudl require a certain wheel to clear and possibly put your track out and in NSW adding 25mm to your tyres puts your wheels out again if you space them.
No headaches for me thats.
My best advice ring someone like Race brakes. Brakes are very important do FARK WITH THEM.
only regreat no using braided lines for looks
