My back box I guess, (the big mufler thing) that your tail pipes come out of. Seems to be leaking water slightly, suggestions Jaguar family?

 

Can you be more specific, as to where you see the water coming from? If it’s the tail pipes, a little moisture is normal.
what year and model is your car?

 

It's not unusual for the joins in an exhaust system to not be 100% sealed which means that water inevitably drips out when the system is cold. You can either ignore it or try tightening the clamp a little. If the water is dripping through a hole in the exhaust system itself, then the structure has corroded and you probably need a new part or some bodging with exhaust tape.

Richard

 

The exhaust points slightly upwards, so lowest exhaust points have condensation drain holes by design.

 

When hot air cools it produces water inside the muffler. Its the act of condensation. Then the new exhaust and car motion, push the condensation out the exhaust pipes, or wherever.