HI there, delimiting the car is no prob. All you need is a speedo convertor, this changes the clocks from kph to mph and also delimits the car. There was some going cheap on ebay or go to one of the companies on here. Fitting is a simple job.
As for the cel light coming on this is not normal, i have never had this with mine and mine, although i don't spend much time at the redline. i would get this checked out and until you do don't drive the car too hard to be safe.