D5 (2005 on) EGR and intake clean - how far to go?

[Wickedy]

I've recently purchased a 2010 MY XC90 D5 with 115,000 on the clock.

I can see the engine is pretty much untouched, so I'm certain it's never had the intake gubbins taken apart and given a clean.

Can someone who's done this job before offer advice on how far to take matters? The main two things I'm mulling over are:

1) Whether it's worth taking the manifold off the top of the engine to remove the gunk as well:
- How likely is it to be so gunked that it has restricted flow, given the larger surface area vs the pipes?
- For the Euro 4, in plain English I believe this job means removing the rocker cover,, then replacing(?) and resealing the gasket (£30). Am I asking for trouble here?

2) Whether to remove the EGR cooler down the side of the engine, or skip it altogether? I arguably don't care about that bit - if anything I don't mind if it's blocked!