I have owned a few road race Miatas over the years and they are awesome. If you are going to replace the rotors and calipers go to NAPA and get the same set up as the Mazda Speed Miata OEM, Hawk brake pads, race brake fluid and do stainless brake lines. This set up was more than enough to handle my 260 WHP Miata at Mid Ohio last year even after an hour enduro (no fade). The rotors are larger than stock to help dissipate the heat better. As for stiffening my opinion is if you are going to road race you should have a cage (mine is a hard dog weld in) The problem with this is you need a hard top and you are going to lose your convertible. The other option is flyingmiata has all different types of stuff to stiffen the chassis. Since I did not go that route I would call them for advice as they know there stuff. Enjoy,Buzz