Removing the catalytic converter will not adversely affect the way your engine runs... the cat's job is to remove toxic matter from the exhaust streams preventing them from entering the outside air...that is it. Removing it will stop this process, but will also affect the sound of your exhaust. You can either remove the cat, or get a "free-flowing" performance cat. Keeping the cat installed will cause some air restriction, preventing your exhaust from reaching its full potential. I'm not a big fan of performace cats becuz in my opinion, if you're really that concerned with power, just take the damn thing off. But like I said.....just my opinion.