lower sline diffuser removal 2007 3 door car

The dark grey "Diffuser" on the S-Line is fake and part of the lower half of the bumper. The crease line around it is just a mould (it doesn't unclip like the facelift bumpers).

However you could probably split the two halves of the bumper but not the easiest of jobs - unless this is what you meant! Yes bumper would probably need to come off and the clips accessed.

i have done it on a sport back

i did not need to remove the rear bumper but had to jack the car up and take the rear wheels off to get access to the screws in the arch once you have done all the screws form sides and underneath start to tug at the end of the diffuser to try and split the diffuser from the bumper, i was finding it was loose but could not understand why it wasn't parting completely turns out there is a screw on the inside of the arch which you can't really see until the bumper and diffuser is split a little, which is a ****** to get to so without taking the rear lights out i just prised the bumper out from the arch and stuck my hand in the gap to get to the screw you will see it if you look directly down towards the inside of the arch, the bumper will squash your wrist and is sore when trying to unscrew but its the only way i found how to do it once you see what i mean will take 5 mins, all in took me about 30 mins