How much went in to replacing the chain guides

It could be, I doubt it, but you said you've replaced the tensioner, and the timing chain in these engines IMHO is bullet proof. It's the guides that fail, not the chain itself.

It's a lot of work, you pretty much have to take the front face of the engine off. If your X5 has over 100K miles they should be replaced as scheduled maintenance anyway according to BMW. Do a search, there's a DIY thread here on the site.

Do you know how much in parts

Did you notice improvments with 10w40?

I spent about $800 in parts, I bought most of the parts from FCP EURO.

No difference whatsoever, like I said, the different weight oils are no magic elixir, you either have to rebuild or replace the VANOS units.

What about as far quite in the engine down

None of the different weights I tried made much of a difference in my opinion as far as overall engine noise. At idle, if you're really, really looking for engine noise, yes you can hear the VANOS giving off tap, tap noise, they call it the diesel effect...lol! I would say 99% of the time I don't notice it.