Just curious if anyone out there has tried fitting their OE Grille fogs into the Boss302s grille.
Since your sig line indicates you own a 2010 Mustang, I presume you're talking about pre-2013 cars. On the 2013s, doing this is easy (see LMR blog entry referenced by M3 Killa). On the 2010-12s, not so much.
I want the same look as you, so I bought a 2012 Boss 302 grille on eBay, thinking it would be a fairly easy matter to open up the dummy holes to accept the stock GT fogs. Wrong.
First, the entire Boss grille is a single piece of molded plastic. The dummy opening "covers" are not separate pieces like they are on the 2013 version. Second,the Boss's dummy openings are deeper, more tapered, and smaller in diameter than the GT's real openings. Third, the GT's grille has mounting points for the fogs on its back side; on the Boss 302 grille, these are not there. So the job is going to require some delicate surgery to open up the holes, and then some fabrication to get the necessary mounting points on either the back side of the grille or the car structure immediately behind the grille.
So, I've not yet done it, because I've not figured out exactly HOW to do it. But neither have I given up.
Lastly, the version of the 2012 Boss 302 grille that has mesh over the openings instead of the solid plates like mine MIGHT make the job easier, but I've not looked into that. This version of the grille did not become available until after I'd already bought mine.