Custom mapping is only worth doing on an FRS which has had lots of mods fitted or if you do not plan on adding more mods down the line as after every new performance mods you will have to pay to have a new map created meaning more ££££

AFAIK Bluefin & Dreamscience also work fine with modded engines as well as standard - in the old days i used to run a bluefin on my car up to 300bhp without any issues