Brass Flywheel?

[Rick-J]

Just got a second hand X6, only ran it once so far at Kidderminster and loved it so much easier than my old B4. It has a brass flywheel fitted and my question is why? Should I leave it on or remove it. I did not see any other cars running one including other X6's. Just wondered if anyone has ran one before and what is their experience of it, does it help or am I better removing it? Thanks