Hello all, i am new to this site and it all is very helpful. I am from Australia and we have a Kenworth T300 with a Mack em 6 motor in it carting mainly rock with a max weight of 42.5 ton, its supposed to be 350 HP but i reckon it only pulls 200 HP.We have had alot of trouble with the puff limiter in front of injector pump as the thread was stripped out of it. When you put the puff limiter in its gutless but when its removed it goes alot better but pours out black smoke and for a 350 HP motor it should go alot better. Does any one know anything about these engines as to how to set up the pump to give motor max horsepower with limited smoke or any other recomendations that could be giving it lack of power. Any help would be greatly appreciated.