Advice on mods? in Products for your Subaru Posted February 17, 2021 Since I got my car, I’ve had some unsolicited advice on what I should do with it in terms of modifications. Someone suggested an “air/oil separator” and a “cylinder 4 cooling kit”. I currently have no mods done to it, and am unaware of any mods that have been done by the previous owner. Are these things I should look into?