A couple of days ago i realised i had a huge crack in my standard exhaust (the pipe between the headers and the cat) so i rang around a few wreckers and got my hands on some Lukey headers for really cheap, after a bit of messing about i finally got it all in but now i realise that the O2 sensor is right up against the engine mount and there isn't a whole lot i can do.... What symptoms will i notice if i've damaged it? How important is it?? Any possible fixes??