I didn’t bother to read through the responses to see if this has already been covered, but here’s how to mod your own CDV (barrowed from a post on another forum).
This was for BMW part # 2152 6 764 872. Places like Bavarian Autosport are selling moded valves for $30. You can pick one up from the dealer for less than half the cost and mod it yourself in seconds. Or you could always mod the one you take out of your car for free.
Here's how: Put an allen key in the small side of the CDV and tap it with a hammer to push the restrictor out the other side. No need to tap very hard. Now it's ready to be swapped into the car. Here’s a few pics:
On the left is the restrictor, the right is the valve without the restrictor installed (big difference):
This is what the parts looks like disassembled:
