Smashing the honeycomb out, as a topic has been done to death, please look around.
Pull your cat out, if its caved in, smash it out as a testing process. If it fix's the issue yourself and your mechanic are getting, then replace it with a larger unit.
Yes - having no cat will improve top end, yes - it will bring in boost in harder and earlier, yes- you'll get yellow stains on your paint and blow flame if your car pops and farts, and yes it 'could' get you a $20k fine (though iv never heard of anyone actually getting it )