My excuse is that I was a "Cessna man" before getting the V-tail!
The POH for my Bonanza (1977 V35B) says:
"INSTRUMENT PRESSURE SYSTEM
Instrument pressure is supplied by an engine driven pressure pump"
The filter is attached to the "In" side of the pump. The pipe from the "Out" side of the pump goes through the firewall, presumably to the instruments.
The guage that I had always considered to be a suction guage, is labelled
"Instrument Air" and the warning light is labelled
"Low pressure warning light".
This would tend to suggest that the air is flowing from the pump to the instruments as in "blow" rather than from the instruments to the pump as in "suck"!
It is filtered twice before it gets to the instruments so it should be pretty clean.
Dr 
The Mad Dr throws YoungAggy a lollipop!