P0157 code

I have this code on my gmc serria 6.0L. I have changed the O2sensor2 but the code comes and goes. Less frequent than before I changed it. I am wondering if the cataletic converter can be altered and remove the code. I/e drill it out, take it out?

Drilling the cat out won't help with this.

http://www.obd-codes.com/p0157