In tinytuner, go to diagnostics> cat diagnostics? and there are 2 tests to set to disable, I'm not at the program right now for specifics but I know they will disable the tests.

Other than that if you leave the rear 02 plugged in and in the exhaust, you can make a 2" or so spacer so the sensor is out of the exhaust stream and then it won't throw a code like it would with no cat there and in the exhaust stream.