I did the same mod a couple of weeks ago and can vouch for the brightness of the LEDs.
I fed the wires through bulkhead grommets that other wires were using.
I pushed the clips back to allow the front of the DRLs to be flush with the front of the fins in the grill, I think this looks better.
I used he self tapping screws to give some additional fixing but these do go into soft palstic so are not all that secure. Once I was happy with the position of the lights I put super glue between the top of the light and the bottom of the grill fin that it sits under.
Very pleased with the result.