I recently bought the Boost RBA and for me, the flavor was weak compared to some of my billet box bridges (like vapeshell). I vape MTL with about a 1.5mm on-deck airflow restrictor. Looking at it, I noticed the airflow holes on the base of the deck were big for MTL vaping. The two big ones are about 4mm combined. While the airflow can be reduced with the ring, I think the air that does go through is still spread amongst that 4mm+ opening and is not the same a traditional on deck airflow restrictor.
I solved this the old fashioned way by rolling some mesh and inserting it in the two large airholes. They each had a hollow center of about .8mm. Doing this improved the flavor for me pretty noticably. I'm still playing with the mesh opening size but for me, there was a definete improvement.
Also discovered after dropping a piece of mesh through one of the air holes in the deck and having to fish it out, that the deck can be dissasembled using an allen wrench and unscrewing the center on the bottom connector of the pod. Positive terminal just pops out.