Not so sure about the air quality point - they're called a snorkel for a reason. In poor air conditions fine dust tends to rise, so raising your air intake can make the position worse (cos your dragging in fine particles, that get through your filers, rather than heavy, large particles that the filter deals with). Lots of discussion on this in Oz and the US re desert driving. TBH 90% + buyers its a fashion statement. Few are going to drive in 3 feet plus water...