Caliper - swap turbo fronts?
 

I've got a '91 C2 (964) I'm want to upgrade the braking performance since I run wiiidde tires(235 f/265r). I've heard that an upgrade to the standard turbo fronts and moving the front calipers to the rear is possible.

1. can/has this been done?

2. would i need to change rotor diameters?

3. is my current master cylinder adequate?

any .02$ would be appreciated!

Go here,
http://www.vehiclecraft.com/Brakes/vciweb7.htm
anything can be done, doesn't mean its the best. In the case of the brakes use one of Doug As' front kits either S4(standard 993 front) or Big Red and 322x32 rotor for the front and get a stock 993 rear with stock 993 rotors in the back. You will have proper balance and way more brake than you will ever need. Use a 993 40bar p/v to take a little more advantage of your ABS(you can leave the stock 45bar unit but you do want to make better use of those fabulous front brakes!)

Stock mc and booster are fine.