He's talking about how I had removed the seal around the filter mouth which forces the engine to suck air thru the ducts molded into the bottom of the seat. That allowed it to pull air directly in instead of thur the ducts giving it more airflow. I put it back because without it the bike does seem to have a tiny bit better high RPM performance, but it killed the low end torque. The loss of torque was much more of a loss then the bit of upper rpm performance, so i put the seal back. It also seems to have fixed my mileage issue where i was getting as low as 31 MPG. I've hit 40 twice since which is almost what i was getting when it was a 1600.
That said, i don't think it is because of emissions standards that they used that seal and duct. I believe while it may have a bit less flow at high RPM's, it's there because it created a smoother less turbulent airflow that works to create better low end.