Hi, am Kevin from Kenya.
I wanna know what will happen if i remove catalytic converter from my mitsubishi colt. Mainly on fuel and sound

it would run better, cats only are an anti pollution device. but here in the US it's a 30 thousand dollar fine to remove them. I assume they don't do that in Kenya

In Kenya they dont mind. Will it change how loud it sounds?

It doesn't change how loud it sounds. Best to keep your cat on.