not sure I've got the cash for my planned brake upgrade so would fitting massive discs with standard calipers make much of an improvement?
Re: Bigger discs?
1. It is hard to fit much bigger discs over a standard caliper - I don't even know if there is such a disc made.
2. The pad contact area would be no bigger on the new disc
3. Cooling would still be poor
4. Caliper flex would still be evident - therefore the pedal feel would not improve
5. If, by some miracle, you did manage to increase the reardation on the front, the brake bias would suffer adversely...
Suggest that you put green stuff (or similar) pads on OEM rotors with upgraded stainless steel brake lines and better fluid. A good budget solution.