bump the pump up a tad,bump up the timeing a bit,get shed of the muffler[it will be very lound] if you dont atleast put glass packs back in place. this alone will make a noticable difference,also how old or many miles has the pump got on it,seen many a diesel wake back up with a proper built injector pump,even supposed wore out engines. adding a banks or ats turbo will make it a completely different truck also...