I have an 07' 323i - I have gone down this path to the point where my dealer replaced the cylinder head about a year ago. The ticking is back and i'm quite frustrated as the car is now out of warranty. Apparently if "this" ticking is related to the warranty work that has already been performed it'll be covered. Time will tell. I know that they replaced the old N51 with an N52 head.
Has anyone else had the their head replaced without success? I'd be interested to find out what happened.