Looks like I might have to fabricate some mounts for my Infinity Kappa 5.25 speakers. The magnet of the Infinity speakers won't fit through the hole. Strange how Mercedes has a goofy plastic frame which the stock rear speakers are attached to. I thought about making the hole larger and bolting the speaker directly to the metal shelf, but am worried that if they are mounted too low and far from the grilles, sound may be dissapating under the shelf and weakening the rear fill. I'd like to get some input first. Thanks in advance.