Clc8797

Yes old truck was of a 300 cummins. Just a diff kinda horse power I guess. So without any mechanical upgrades (turbo injectors etc.) what is a safe hp gain and will Mack allow us to add around 50-75 hp just with a new ECM update? Or will they try to tell us driveline will fail without upgrades?

Hey everyone. I am new to this site and have been reading a lot of post seems like a great helpful community for Mack trucks. I will be on here on my dads behalf as he is computer illiterate. He recently purchased a 2003 chn613 400hp dump truck with 16 ft box and 15ft pup. It has 603,000mi it is a really clean. The truck seems kind of sluggish doesn't have good throttle response no lights are on in the dash just seems like it is detuned and the computer is holding it back due to emissions bs if I had to guess. What is the best way to check on maintenance records and check what tune is on the ECM ? Are there plug and play modules for these engines or does it all have to be done through a dealership? Any common break downs or things that need to be looked for on this model? Thanks for all replies and advice