I have a 2001 3500 ext. cab, stock except for a banks bighead actuator. Under heavy acceleration I get a loud chirping sound. I have had it to 2 dealers and numerous other mechanics and no clue as of yet. I was told by a dealership head diesel mech. that it was the actuator. NOT. I was also told by cummins mech that it was the lift pump. NOT. The pump was weak but not the problem. I am about to put a banks powerpack and a exhaust brake next week and then I may find the trouble. If anyone has any suggestions I would appreciate any input. I also would like some input on the powerpack and brake system if anyone has had any experience with them. Thanks Greg