Researched a bunch but now confused. Can someone please explain how these "disks" and the end caps work? It looks like end cap equals ten disks, but what does that mean? Does adding disks/end cap make it louder or quieter? How do they work? Thanks.

 

the disks have 'spacers' where the screws go through. stacking the disks gives more airflow (less restriction) so it makes it louder. less disks, less airflow = quieter

thats kinda it in a nutshell. there are a myriad of combinations that you can try to tune them to your particular needs. less disks, no endcap, more disks, endcap, etc....