Another Aygo - woo hoo! And doing some superb MPGs too. Like the wheel covers. What LEDs are you going to use, are these for DRLs ?
Are you planning to block the whole grill or just the bottom ? I've blocked the nostrils (upper grill, either side of the big T) on mine. Hard to tell if there is any difference yet due to the non-stop gales we've been having.
Going to block the bottom when it gets colder, and then maybe look at the underside in spring - too cold just now