I have a 1995 F-350 with 312,000 miles. I would like to build the engine a little bit(maybe 400HP to the rear wheels). Right now it is completely stock with a Edge 6 Position Tuner. It has cold starting problems which I assume the injectors are the culprit since I changed the glow plugs, IDM, and Cam Position Sensor. I am thinking of rebuilding the injectors, and I have an option to get a 160cc upgrade for free. Is this a good idea to do, or should I think about doing a overhaul before thinking about building any real horsepower?