I have done some research but i am still somewhat confused. I have read that 99 interceptor engines had the romeo engine which the 01-04 mustang have I recently put a 1999 Crown Victoria interceptor engine in my 97 Mustang gt. I want to enhance the engine performance on it but first i want to know if 01-04 gt mustang performance parts would fit the 99 interceptor engine. Are these engines the same in any way? And if so does that mean that the performance parts for the 01-04 mustang gt engines would fit the 99 interceptor engine? Any help appreciated.