I gutted mine and have no issues with them gutted.
However I do notice a loud tinny sound when the car is cold as air moves through the empty chambers.
This goes away when the car has warmed up.
I notice your in Guadalajara. I go to Puerto Vallarta once a year and guess you have no issues with smog testing there.
How to gut pre cats
I used this to do mine. Back cat took 15 minutes, front one took about 3 hours.
I had my car on a hoist, which made it esier. Also you will need MIL eliminators for the down stream O2 sensors.
I got the ones from ponyexpress.
www.ponyexpressperformance.com 
