As a rule of thumb you need to upgrade the injectors when you fit a camshaft to your Cooper S, you'll find the stock injectors are starting to hit there maximum duty cycle at the top of the rev range with the normal bolt ons Pulley CAI Intercooler.
These 550cc EV1 injectors are supplied as a direct replacement to the stock inlet manifold, fuel rail and inector connector, the 4 that we supply have been on a flow bench and have all matched within + / - 1%.
A live re-map/tune of the car will be required to run with these injectors when fitted.