Remove catalist

I live in U.K.. I have a 1999 Tahoe 2dr, 4wd, 5.7 vortec.
In the U.K. I have no need to run catalists in the exhaust system.
If I remove them and fit fire pipes, will this upset the sensors before and after the catalist?
Or, can I just leave the sensor after the catalist outside of the exhaust pipe after removing the catalist?

You will turn on the check engine lite and set a code

Thanks for letting me know what the resulting problem of removing the catalists will be.
Is there a way of removing the catalist without upsetting anything?
Can't see the point in shelling out for catalists when not required by law.

The only thing I can think of is a change in the PCM programing so it doesn't monitor cat. performance. I don't know if this is possible,but some of the after market electronics people may be able to help

Thanks for your input Bronco2