In Andy's defense, his math was fine for what he was trying to show. He was expressing the percentage difference in piston area and simply factored out pi and the radius conversion to simplify the math a tad. The answer's still the same - ~24% difference.
That is correct. When comparing areas you only have to compare the square of the diameters. Everything else cancels out. Old engineer trick. Just do the math that needs to be done.
The Wilwood calipers will reduce brake force over a factory 2.75 caliper. You can get the brake force back by reducing the size of the MC but then you might cause a problem with the rears. There are no free lunches with brakes. Everything has to stay proportional and in balance. Dropping piston area on one end of the car by 24% with no compensating changes could be dangerous.
