This came with my RE boost gauge, never fitted one before so no idea what it was. I just connected the black pipe from the spare nipple on the UIM to the back of the boost gauge. The only thing is the boost gauge makes this really loud rattling noise!

Is this bit supposed to go on the nipple before the black pipe or what?? One end has a bigger hole than the other:

 

It is a restrictor. Putting it in the line should smooth out the needle movement slightly and should stop the rattle. Just splice it into the line somewhere.

-Max

 

just fitted it as you said, spliced it in, and its perfect now!!! thanks very much