Hi there... Bought this for my wife in TX and never had a problem over there... All stock except for K&N air filter. However when we tried to smog in CA we get this. 130K miles. 15 mph HC max 51, meas=15, CO max 0.48, meas=0.01, NO max:419 meas= 1067 Fail 25 mph HC max 35, meas=13, CO max 0.46, meas=0.01, NO max 706 meas=242 Pass We've seen some threads on forums about running 87 octane vs standard 91 octane and letting it run for a while before testing it, but those seem to be mostly for CO issues... What about for NO issues? Appreciate any and all contributions.