ive heard that if you move the o2 sensors further downstream in the exhaust (away from engine) that it helps to fool the computer into changing the fuel ratios because the concentrations of the gases change as they move through the exhaust tubing. of course ive never tried it or anything but maybe some one here will confirm and then maybe you can use that to remedy your situation. also, i know that ive never seen "performance" o2 sensors, i figure an o2 sensor is an o2 sensor. what you can to however is pull out the stock ones and try to open the slits in the sensor end (i think its open). supposedly that will allow more gas to flow through and will help to fool the comp also.