I just got an '03 TDI, which according to CO law, I have to run through emissions every year. Cars '04 and newer only have to go every other year. Anyone know if it's hard to pass the CO test? Ever have to do mods or anything to pass? Any additives or tricks that help? The car is bone stock, and doesn't appear to be smokier than others (though it smokes like crazy after a real cold start). Any tips much appreciated.