Vctor, I did as you said and put the two stage filter in, and it does seem to me that it blocks a bit(or it could be in my mind)more air, but the fan speed seems unchanged. I also called the SM at my servicing dealer(not where I bought the car). He said just to put it in, and there is no need for a re-pro of the ECC(he did know of this type of filter).

I did not plan on going to the dealer for this re-pro for two reasons. First, Volvo only recomends the re-pro...they do not say ONLY use this filter after the ECC is reprogramed, so I could have put it off IF it was even needed. Second, I think(FWIW)what is ment in the instruction booklet is for models with ECC that DID NOT come stock with the cabin(carbon or plain old stle)filter(or bracket)DO need the reprogram due to the need for higher fan motor speed ect.

Anyhow the filter(both models) is in, and it does save my ass when I am stuck inside the Lincoln Tunnel at rush hour(and in summer the temps go into triple digits), and I always have the good luck to be right behind a 40 year old bus.

I dont like to run the ECC in the "rec" mode for too long, but if I have to I have to. For the rest of the time the activated charcoal cabin filter seems to do a much better job than the paper only model.