I'm restoring a 2003 MCS with JCW kit. It's currently on stands as I'm in the middle of several projects. A couple of days ago I was running it. After 10 or 15 minutes, it started making a noise from the front right. A loud ticking. It sounds like the source is around the supercharger pulley or belt tensioner but it doesn't sound like recordings of heard of SC or tensioner noise. When I listened lower, by the crank pulley, the sound was significantly quieter. After a few minutes it stopped for about a minute and then came back. At that point I shut off the engine.

For background, I've recently done the following work:
installed a rebuilt cylinder head
new timing chain, guides and tensioner
ATI crank pulley
new idler pulley
SC oil service and new water pump

The belt tensioner is NOT new.

I've ordered a stethoscope but wonder if anyone recognizes the noise. I'm attaching a recording of the sound (below).

 

I'd say it sounds like an injector. You may disconnect them one by one, starting from 4th and see if the noise changes.
If you want to exclude the SC / WP - just take off the belt

 

Thanks for the reply. I posted this in my restoration thread as well and earlier today someone replied that it sounds like injectors. They said that their car has been making this sound for years. It just started on my car and seems to be intermittent. I'll certainly add injectors to the list of possible causes and test as you suggest. I'll try removing the belt as well. Of course, it will be considerably more difficult to diagnose if it doesn't become more constant. Thanks again.