As Ash said, you don't need to cut the reinforcement bar to go from sport 8p1 to sport 8p2.
You also don't need to cut it to go from 8p1 sport to 8p2 s-line.
I'd recommend facelifting to s-line instead, looks a lot nicer.
You will have to convert the rear as well though, but that's pretty easy, all you'll need is the rear bumper and diffuser.