Speed Weed

I'm trying to improve my fuel economy in my 2007 accord 2.4l. I'm getting exactly 20.5mpg on any grade of fuel (87,89,91), almost all freeway miles, always with cruise control, (60,65,70, no difference in mileage). Tires are good and inflated to spec, suspension is strong (IE not rolling around causing speed loss).

I checked the brakes, they are not dragging against the drums/ rotors
I replaced the spark plugs (looked like running lean)
I replaced the air filter (the other one was dirty but not terrible)
I sprayed off the MAP/MAF sensor with electronics cleaner.

Now I am looking at doing the valves and/or the 02 sensors, but here is my question. Are the up and down stream 02 sensors special made for california? I keep seeing federal VS. CA emissions on the various brands of sensors. What is the difference? Can I buy two no name sensors or do I need the $100+ CA emissions ones?

2skys1imit3

not sure what they do in SoCal about the O2 sensors but a lotta parts usually have a CA specific

when i lived in CA, just find a good smog shop, only go there and it will make testing easier