Those aren't OEM LEDs. They also don't include reflectors which are required by law... you will need an R32 bumper with the reflectors.
....Ah! I thought the reflectors were a legal requirement but wasn't sure. Is that requirement in the UK? EC?
Why aren't such reflectors on the GTI? Sorry, I'm a little confused.
It's an EU requirement IIRC and all the OEM lights on the Golf (normal, LED, R32/Ed30) have them running along the lower edge as Very Cherry says.