I bought ducts following TUN3D's posts. To make them flush you do have to kinda customize them with a hot knife. Especially on the driver side where on the 135i there is a horn in the way of the duct. I cut the upper side of the duct to make that fit and had to secure them with metal wires so they will hold their shape. I secured them with metal wires because as TUN3D mentioned, there are no brackets that will connect to the end side of the air ducts. I drilled holes in the ducts where they are not visible and wired them to fit before placing the bumper.