Exhaust system CAT

Hi Guys,

I have a E46 318i
About 2 years ago I took my car to Supa-Quick and I cut out my last box {the box right at the end where the tail pipe connects]

I put in a center to center 1:1 box with a double tail pipe. this made my car sound louder it sounds nice when I rev and stuff BUT its still not that natural BMW sound {if you know what I mean}

I have been thinking about taking out my CAT, but I am really stressed about doing this I am worried it might cause engine damage or so because it has a electronic sensor on it and if it disconnected what will happen?

Basically I need to find out the following:
*will it cause damage to my engine?
*will my fuel costs increase decrease?
*Will my car climb faster quicker?
*in general> is it a good idea or not at all?

I was told that the cat is there only to try clean up your fumes nothing else

has anyone else cut out their cat??

thank you
Chase-GP