I did this mod yesterday with a buddy of mine and cannot believe why I waited almost 20k miles before doing it. It is like driving a different car and I finally have full control of my clutch and gear shifting. It is silly that BMW even puts these in.
I highly recommend doing this mod and don't waste your money on buying a modified valve. Just modify yours by following this: http://www.billswebspace.com/BMWCDVModification.htm
Took me 2 minutes to pop out the restrictor plate and the plastic ring. Super easy.