Here is something interesting then, I bought my Tenere in 2014 new from factory, have been running it from factory with DNA stage 2 filter for like since I got it without any mods. I am not sure how it works, What is a DNA stage 1 + 2 filter? It does have a rubber insert inside the filter like this? Does this mean, it has a DNA stage 2 filter with a kind of air constrictor?