Really? Source?

AFE filters are generally inferior to stock filters- they trap less dirt and any 'increased airflow' is immaterial in a turbo system.

But the NEED that many owners have to DO SOME MODS is powerful, and air filters and CAIs are easy money. (Especially the CAI where people can open the hood and marvel at their mods)

(Suggestion: Stock filters reduce flow as they trap dirt (all filters do) so simply replace stock filters more often.)

Oh, why does filtration matter? Take a car with stock filters, drive it- test the oil (UOA) every 7500 miles. Then use one of the "hi flo" filters with less filtration efficiency. Drive it- test the oil. Look for contaminants in the oil and wear metals. Compare.