The Squadra chip has received rave reviews from owners on alfa155.com, can't remember if there is a v6 owner on there with one fitted though. The only thing that puts me off is the use of super unleaded as its rare where I live but as you use it already...........go for it
Air filters, do you mean a direct replacement for the panel filter or an induction type such as K+N?
I'm using a Ramair panel filter at the moment but looking at some king of induction kit. K+N and Green both do one for the V6 but locating one is the problem, I'm told Hlafords do them.