has anyone used the super chips 3855 tuner yet. My brother has one on an 01 Cummins and it seems like the timing is off. it has a bad top end engine rattle ( even on fuel mileage the lowest setting )that it dose not have with a Deoblo power puck, i have the bombed truck and it dose it on it, but it doesn't do it when it's off. is this natural, or is this bad news.