It is the "Intake Muffler":

http://www.realoem.com/bmw/showparts...37&hg=13&fg=20

You would need the intake muffler, an air filter element and the spring clips. You may or may not still have the rubber boot to connect the intake muffler to the "suction hood".

Looks like the intake muffler for the 4.6is might be cheaper:

http://www.realoem.com/bmw/showparts...72&hg=13&fg=20

The 4.6is intake muffler has an opening to let outside air in. It works off of a vacuum advance but you could just leave it open.

I am installing my Dinan CAI and thinking about selling my stock air intake but it will not be for a few weeks.