I've got the excate same problem. We both live in states where emissons are required. I've recently learned both the anti foulers and tuning are illegal for non track cars.
You can get a tune done which will knock out the code depending on if the tune shop will do it for you.
I'm now looking at getting a COBB catted down pipe , my hope is that I dont need to get subaru's and can get aftermarket and pass emissons. My good news is after replacing front O2 is that with a drive cycle I got a cel for the good ol p0420 code.
My .02 .. It all depends which way you are willing to lean