You don't need any special tools-just regular sockets and wrenches, etc. When I installed my RT cat, I had to cut the wires for one of the sensors so I could slip the closed end of the wrench around the sensor and then remove it. if I had to do it again, I would cut a slice out of the wrench so I could slide the wires through so I wouldn't have to solder the four wires back together and would also end up with a custom tool. For some reason I did not get gaskets with my cat so I went to an exhaust shop and got a sheet of gasket material and cut my own new gaskets. I feel it's definately a good idea to always install new gaskets with any new exhaust component rather than reuse old gaskets.
I really like the RT cat-place it next to the stock one and you really see why it flows more. Keep the old cat and mounting hardware in case you ever have to reinstall it. I know there is a rule about replacing any cat before 5 years or without a documented reason for the original one going bad. I haven't had to go through emissions since I installed my cat so I don't know if it will be an issue here in VA.