I have a 65 C10 and installed an 08 5.3 LMG form a Tahoe mated to a 4L60e. It's a weekend driver not a racer but I do like to tromp on it occasionally. It's entirely stock except for intake, exhaust, rear o2 sensors deleted. I sent away the computer to have the usual stuff done, remove vats, emissions, active fuel management, etc. The truck starts, runs and shifts great. I've only run it 300 miles. I'm just wondering if some fine tuning could be or needs be done to have it running at peak efficiency?