This is a how to for the Reference area.
1. Purchase a new metal body BOV.
Turbosmart Kompact make a Plumback model : TS-0203-1233 or Dual port version if that's your thing:TS-0203-1023.
GFB make equivalent model versions: Plumback Mach 2 TMS T9133, Respons TMS adjustable bias dualport T9033 and the big banana T9533 with electric in-cabin control of venting bias if you really need to...
2. Best done with the engine cool as you need to work near the radiator and turbo. Under the bonnet the BOV is found on the lower front RHS of the engine (LHS as you stand in front of it) attached to the bottom of the charge pipe that leads up to the intercooler. BOV1 by Murray, on Flickr
3. Start by removing the cool air duct to the air filter housing, then remove the RHS radiator fan (LHS as you stand in front of it) by removing the two top bolts, raise it a bit then undo the plug from the loom. Then get under the car (it doesn't need raising much to access it, approx 30cm of so on a jack and use axle stands under the chassis for safety) and remove the front undertray - 4 bolts and various pop-clips under and to the sides.
4. Now with a bit of room to work you can undo the hose screw clamp (red arrow) between the BOV and the charge pipe from above. Also slide off the vacuum control pipe (blue arrow) that comes in and attaches to the nipple on the RHS of the BOV. BOV3 by Murray, on Flickr
5. Now from under the car, using pliers squeeze the lower spring clip on the bottom of the concertina (recirculating air) rubber pipe that connects the BOV to the intake pipe below it. If you squeeze the clip the right way it will lock open and make life a lot easier. Now you can twist the BOV out of the charge pipe and pull it up off the intake pipe together with the recirculating pipe. BOV4 by Murray, on Flickr
6. Now just transfer the recirculating pipe off the old onto the new and reverse operations. I used a bit of silicone oil spray on the pipes to make it easier to slide them in. Unlocking the spring clip is a matter of gripping with the pliers and twisting them the right way to release the catch.
Voila - fitted new BOV. BOV5 by Murray, on Flickr
7. Don't forget to reattach the vacuum control pipe, refit the fans and reconnect the electrics plug, reinstall the cold air inlet and then reattach the undertray. Try not to leave any left over clips.
8. Go for a drive and check everything runs well, and enjoy improved throttle response.