I would probably post this in the escort rs turbo section....

But any way, yes it is probably due to the higher output of the cosworth pump. Your MFI unit actually relies heavily on fuel pressure to do its job (it adjusts pressure depending upon mfi flap position).

Your fuel pressure regulator should in effect 'regulate' the pressure so it maybe tired.

Tell them when you get the car rolling roaded and any good tuner will adjust the fuel pressure accordingly or replace the regulator if this is indeed tired.

Good luck

Rob,