The original open fog grills come with covers on the rear. The OEM grills were only on the first Mk5 GTI's and soon disappeared to be replaced by the solid grills.
The OEM open grills can still be bought, cost around £90 for all 4 parts, they pop up every so often on here for around £40-£50 second hand. Copies of the original open fog grills can be bought from eBay for £20 ish (these have no covers on the rear though), AFAIK the fit is pretty good but you'll be letting all sorts of grit, rain and crap from the roads into the front of the car. No idea on quality though.
My OEM original open grill with rear covers....