The O2 sensor uses a 22mm wrench. Realistically you don't have to remove them from the pipe unless you are also upgrading the downpipe (the downpipe and swaybar are commonly upgraded together as they share labor). If you are using the same downpipe and only upgrading the sway bar, then you do not need to remove the O2 sensors from the pipes, you can simply unplug them (pictured later).