Oxygen Sensor Replacement

[gotboost]

So Ive been getting crappy gas millage at 22mpg mixed driving, deciding to give a new primary 02 sensor a try, has anyone used on of these splice in sensors....
http://cgi.ebay.com/ebaymotors/NEW-B...mZ180274263584

Or should I just get the OEM one, and also whats the best/cheapest place to get one. Thanks

Also the car has 66k on it, the fuel filter has never been replaced, should I replace that also, and the spark plugs were done at 40k, should I replace those too? Also the air filter was just done. Any other ideas about the shitty gas millage, I went to the dealer and they said it was normal, but I think they are full of crap.

[MikTip]

Get the OEM 02 sensor...

ECS has them on sale quite often.

www.ecstuning.com

[jursch2211]

I know some might disagree but do both of them and save yourself some time later!

[tj19855]

I have all 4 oem oxygen sensors if anyone wants them for half the price, I wrecked my Audi and never got to install them.