Is it a resignator? Anyone removed it? It sits under the air filter and the air has to go through it to enter the filter. Surly it would be better removed?

If the air has to pass through this part before flowing through the filter I would guess that it is a type of diffuser to spread an even air flow across the filter.

Been discussed before in this thread, http://www.briskoda.net/forums/topic/237139-what-does-this-bit-inside-the-airbox-do/

Cheers for that. Took it off and also blocked up that.massive hole at the back of the air intake. Its goin back into awesome to have a miss fire looked at next week. Ill probably get them to put it back on the rollers again to see if its made any difference since last week.