I'm getting the valve cover gasket replaced and was just reading up on it. Several sites mention that Vanos seals should be done at the same time.

From reading a bit about it, severe temperatures are a big contributor to vanos issues, and we're in a fairly temperate climate. I don't feel like there's any problems with torque or MPG, but it's mentioned that it's only after replacement that people feel the difference.

Is this necessary/advised (specifically for M54B25 with 170k miles and no sign of it being done previously)?

If so, what's needed/what costs/is it something a non-BMW specialist indy can handle?