1.9 Z3 exhaust vibration damper - where does it fit and is it necessary?

[TriumphZ3]

I've just replaced the front pipe / cat section of my 1998 1.9 Z3 exhaust but am wondering about the part to the right in the online pic I found, below. I'm assuming it's a vibration damper but where exactly does it fit? My original exhaust has two dimples on the bottom face of the pipe, one dimple very near to the centre support bracket which the clip of the damper fitted into, and one closer to the silencer joint, but the new genuine BMW exhaust doesn't have the front one. So: do I actually need this part and if I do, where does it go, does it just clip where the single dimple is, or how do I measure where it needs to be?