I purchased 1 of his hybrid 6.4's. Had it installed by my mechanic, the motor had about 1000 miles on it and it broke the tip of the intake valve on number 6, fortunately it broke above the retainer, and didn't drop a valve. He said he had class action law suit against the valve manufacturer, so I had to pull the cab again, pull the heads send them back, he replaced the valves, didn't cover the labor for the cab and pulling the heads and I have about 8000 miles on it and it runs great very happy with the motor, felt he should have covered the labor for the broken valve.