I was mapping a 1600 16v fiesta on bodies and lairy cams a few weeks ago on a set of these nasty sock filters and it did exactly that, digested one of them down the throttle body and into the head.

Luckily we managed to yank it out and I pulled the others off till they could be replaced with a decent sausage filter the next day.

The customer then saw first hand what I meant about how shite they were (had already been telling him to bin them) as it gained literally about 20bhp when they were gone, they are just SO restrictive, which is why they get sucked into the throttles in the first place because the airflow pulls on them so much.

REALLY bad idea to use them.