Well, I did put in an oil catch can on the weekend, it may not be a "Provent" but it will do the job, Its a nice small unit (400cc) and has a drain on the bottom as well as a inspection port at the top, inlet and outlet, as well, it has a neat clear pipe up the side (so as you can see the level of oil in there) I have hidden it in behind my aircon condensor, fits perfectly there, and I have run the hoses round behind my fuel filter, I have not actually put the venting back into the airbox, I have fitted a small airfilter on the return hose, I'll see what occurs there. But happy with the instal and how its working. (Pics later)
I also whilst doing this, checked over my turbo hoses. I have installed my Samco hoses, and did notice quite a loud turbo whistle after my exhaust was fitted, but, what worried me was that I could see an oily build up around the top of the intercooler just near the hose connection. I found that the inlet turbo hose clamp (a funny looking one) was not sealing the pipe all the way around onto the intercooler, and that the whistle I was hearing was actually escaping boost when the turbo kicked in. The exhaust place must removed all the hoses when they were making the new dump pipe, and then put on the weird clamp that didnt seal properly. I have replaced the clamp with a conventional hose clamp, and now has a perfect seal, all whistle has gone. I cleaned up all the oily residue in the area, and I'll check it again soon, to make sure there is no leak. I was worried that maybe the intercooler was cracked and leaking, but after the whistle stopped I'm confident it was the problem.
One thing tho??????? The 2.5lt CRD does not seem to have a MAF sensor in, or, on the intake. It may be all in the boost control sensor, maybe an "all in one" sensor??????
Kj running better on takeoff now, (must have been that loss of boost at start off

) but, funny I never felt any other loss in power when driving any other time, just the whistle.