I would map it first and foremost, it transforms the car, increases engine safety, increase performance dramatically, reduces the VOD, You can map you car with a fuel pump for under a grand.
Being honest I don't think the stopping power of the the 4pots is noticeably better than the standard 2 that are on it...just helps if your pushing it on the brakes don't fade as much..3 or 4 heavy brakes in a row and my old 2 pots would be soft as sh!te..exhaust system would be best tied in with your remap to get the most from it