Your Mazda RX7 FC still has some very impressive stopping power.
If coupled with up rated disc's and up rated pads these are more than sufficient to keep your RX7 top of its performance.
Remembering that for every 1kg of un-sprung weight you add to the car is like adding 8kg of overall weight to the car, so on a stock or fast street car, adding a big brake kit is equivalent to adding approx 80 to 100 kg of weight. In my opinion pointless unless you have the bhp or track car to match the performance needed.