Recently I've fitted this new upper grill, its supposed to be like a HDT / Holden Dealer Team type aero grill but its made buy another manufacturer, its real carbon cloth over a fibreglass body and was noticeably a little lighter than the the stock grille, I am thinking it would in this slot style be like a partial grille block
Before:
After:
Really happy with the result, its suits the colour of the car too.