I just replaced my cheap nasty plastic grille on my 07 cts with the E&G Classic mesh grille (upper and lower). The factory emblem comes off of the cheap grille by using a gasket scraper. Then you'll spend an hour trying to peel the old rubberized tape off to reuse the emblem with new double sided tape.

There are a few small studs on the outer leaf emblem that fit into the furnished round emblem mounting plate that comes with the new (E&G) wire mesh grille to make sure its aligned. So as long as it's not a "V" grille, the aftermarket mesh grille for the non-V CTS will accept the emblem.