More Knocking noises on a 2.5 V6 156 (subtle ones)

I read the post from David about a definite knocking noise from the front of
his car. Not so sure I'm suffering from the same thing. Whatever it is,
it's very subtle (quiet), sounds like it's related to road speed rather
than engine speed, comes from the front passenger side (seems like that to
my ears anyway) and occurs basically when the vehicle is moving. You have
to listen for it, but it is there. Any ideas?

Plus, when starting the engine it makes a sound like somebodys brushed the
downpipes with a wire brush briefly, then all is normal. Done 91000 miles
so far...

Rgds

Stuart