I started making these but ended up ordering a new frpp intake. They are functional as is but some epoxy and smoothing with a file would cover up the rough parts.
The original inserts were seperated and glued in with sleeve retaining compound. I even kept the arms that hook up to the motor for a stealthy stock look.
They get rid of the butteryfly valves between the intake manifold and head that rob the car of about 10 HP. They make the hole the air goes through smaller and try to swirl the air as it goes into the head. Supposedly they help with low speed drivability and maybe gas mileage, but no one has noticed a difference after swapping them out and getting a tune for the delete plates.