GrimmSpeed BRZ//FR-S Intake - Manual (Page 13)

17. This step is critically important, so proceed with caution! The air filter features an
internal radius that is very effective in speeding up the intake air as it passes the
MAF sensor and can affect AFRs greatly. The base of the filter should sit 1 inch from
the flat face of the MAF flange (figure 21). Tighten the hose clamp until the filter is
securely mounted to the intake tube.