i too like this thread. in addition to the questions above, when do you really need to have your ride calibrated? my troop although less than 3 years with 20k mileage exhaust black smokes specially if you need more speed. kakahiya. but i have seen this in most isuzu rides. is this really normal or i need to have something adjusted. i just had my 20k PMS done and changed fuel filter as well, but nothing changed.