It is plastic and it isn't really nessecary to install a BOV because there is a recirculating BOV in the compressor housing already.
The car doesn't really respond well to two BOV's........
I tried on my S60, I bought a second pipe from the IC to the TB and installed a special plastic T piece.
I used an adjustable Blitz BOV but it had to be set almost completely closed to get the thing working 99% and that 1% left really bugged me on higher speed/RPM.
The throttle became VERY sensitive.
If you want to disable the standard recirc. valve you would have to take it out of the turbo and block it to make it 100% effective.
Edit: If you want the sound you could opt for an open air filter (cone?) but you would have to remove the airbox.
This is a picture of one but the MAF was disconnected at that moment.
I checked inlet temp's and without any shielding it didn't run any higher in temp's compared to and airbox except for a small moment when the car had run idle for a while.
You could fabricate a shield on the left side of the filter.
[This message has been edited by Johann (edited 07-20-2002).]