I have never heard of anyone successfully installing the larger 550cc injectors. Every report I've ever read says the car runs "pig rich" and they end up going back to the OEM SRT6 injectors. A higher volume fuel pump and an adjustable fuel pressure regulator is the answer to "leaning out" in most cases. Note also that the stock fuel filter has a built in fuel pressure regulator. You need to get rid of the stock fuel filter too! As someone else suggested, let us know what mods you have installed on your SRT6 so we can better offer suggestions for you. My first suggestion is to remove the 550cc fuel injectors and change your oil as there is likely fuel contamination in the oil now.