Installing rear under deflector(OEM Aero kit)
 

The instructions say you have to remove the rear bumper, is there a way in doing this without removing the bumper?

any tips?

Yee, remove the little plastic tab (cut it or sand it down) and the clip screw on the rear flares (use a flathead screwdriver to lift the metal clip)

So it ends up being held by the wheel well screw and the 3m tape, which is perfectly fine. You just need to give it some time (1 day or so) so the tape reeeaaally sticks on, as with any tape... (no car wash, no going over water filled pot holes and splashing water all over the road... stuff like that)

cant u still make the slot? u can reach in the bottom of the car to stick in the aligator clip

Then im pretty sure you can drill the other hole too. I dont know how much clearance you have by going that route to drill, if you have enough, then go for it.