Standard VW dual port cylinder tins have an internal air vane to properly channel the air flow. However, aftermarket tins have left this part off. Why? makes it cheaper for them to produce and they figure, if you can't see it, you don't need it.

We know better,  VW engineers would not have put this tin in if it was not needed.

This is a faithful reproduction of the VW partto improve air flow.

These parts are professionally laser cut from 18 gauge steel, production bent, powder coated, and spot welded to the aftermarket cylinder tins.

If you install these yourself on your aftermarket cylinder tins, The preferred method of attachment is by welding. Pop rivets are
also acceptable. Screws or bolts are not recommended as they
may work loose over time.