Back in the day, the WRX didn't even come with a hood scoop insert, at all! Zero Sports made one. Then, the next generation WRX arrived WITH an insert -- oddly similar to the Zero Sports model! Who says the OEMs have a monopoly on innovation?
The Zero Sports take on the Legacy scoop insert is to bring the splitter vane closer to the front of the scoop opening, to get more air distributed to the under-served front of the intercooler.
Comparison with the stock piece:
Zero Sports Cool Action scoop insert -- click me!
Click the link for pricing and to order.