The Green Lantern

So i have an 04 gt and its got bassani x-pipe with high flow cats on it. Put new o2 sensors in about a month ago and its throwing p0430 and p0420 which i know is the two cats lean. I have a diablo tuner and i'm running just the 93 octane that comes on it. Just confused on what this could be. Could the o2 somehow caught something an burned the wires? I had to extend them because they were to short for the aftermarket xpipe. I know I wired them right cause i drove a good 1000 miles before the ses light came on. I seem to be getting gas mileage just this tank. Usually average 18mpg and thats all city. I hope its not clogged cats cause i dont have money for new ones. Any help would be great thanks guys!

amoosenamedhank

so you're getting bad gas mileage this tank? I'd keep your eye on the mpg but if it ends up just being a code, you should be able to disable your rear two 02 sensors with the tuner.