Yes..you have to snap them off because the 4.8 is bumper has slots that these clip on to ,but yours doesnt.
You will find that just with self-tapping is sufficient,no need to glue it .
I have a pre-facelift and I fitted the 4.6is front spoiler and I also had to cut off all clips and to fix it I had no choice but to permanently glue it with black windscreen sealant..