Code 41 shoule be pretty much limited to the heater circuit of the O2 sensor. Not a whole lot of unrelated problems can set that one off.

Since you had exhaust work, you might want to look at the wiring down at the sensor. They may have pulled on the wiring, rubbing thru some insulation somewhere within the wiring that belongs to the car.

What are the other smog numbers? Sometimes you can play them off against each other. For example, advancing your spark timing a little bit can improve CO & HC while making NOx worse.