Re: Pollen Filter
I too have a 156 1.8 veloce (2001) and have just changed the pollen filter. Very easy, if the screws are unscrewable! The filter on mine is accessed via the passenger side grill under the wiper arm. Unscrew the four screws holding it on and pull off the rubber seal on the edge. You can then wedge up the cover and you will see the filter underneath - held in place with a rubber band. Flick this off, change the filter and refit in the opposite manner.
Take care when reassembling to make sure all fits correctly, esp against the windscreen. Takes about 5-10 mins, IF the screws come out.
If they don't then you may have to either wreck the plastic cover then when the screw heads are exposed undo them with molegrips or similar, or drill the heads off and unscrew with molegrips once the cover out the way. There are products which aim to undo difficult screws, but I've not managed to make them work yet!