I have heard alot of stories that mitabishi 7 to 8 evo disc brakes and calipers fit onto fd3s rx7s with very little modification can anyone tell me if this is what mods need to be done... I need a inexpensive bigger brake upgrade?

 

It will kill the brake balance on the car. The pistons in the Evo calipers are too large.

 

I have a friend with evo 9 brakes front and back on a first gen using fc front spindles and custom brackets. Get a brake proportioning valve and you're golden.

Balancing the brake bias with the proportioning valve and pads will be key. GL