NO thats cat efficiency
Bad o2, or bad cat. you could try a bottle of Mr. Gasket Cataclean
Proper diagnosis is needed. Scanner readings on upstream O2 should be above 0.800 and below 0.200mv to much activity on back O2 might be reason. Also watching MAF readings, and misfire codes/readings.
Also take a look at Long Term and short term fuel trims.