my nissan sentra 98 has two catalyst, and i am spending too much money in gasoline, actually i run 20 milles per gallon, factory specs are 32 mi/gal.

Does someone know if i can remove the firt catalyst system and remove the heatedoxygen sensor to increase my performance?, i think this car has an exhauts system forCalifornia regulations.

 

If you take off your o2 sensor and cat you are going to throw a code and have your check engine light on.