GrimmSpeed BRZ//FR-S Intake - Manual (Page 6)

8. Remove the rubber isolator grommets from the stock intake. To do this, push the
metal sleeve out of the rubber grommet and then slide the grommet off of the tab
(figure 8). The GrimmSpeed intake system reuses these, so go ahead and install
them on the grimmspeed airbox (figure 9). Using a bit of o-ring lube or soapy water
will help the metal insert slip in nicely.