Recently I installed a pair of Infinity Kappa 6x8 in the rear. These speakers rattle the car like crazy. Previously I didn't have speakers in the rear, so I'm not sure how stock would've sounded, but I'm sure not the way these do. I directly bolted on the speakers to the rear brackets and taped the foam that was included with the speakers to dampen some vibration, but I guess this isn't working.

What have you guys done when you guys installed aftermarket speakers. Is there something I'm missing? Does anyone have any experience with XTC Baffles with the FD?

 

if the speakers are secured properly, it's probably the speaker grille that's vibrating. Sometimes 3-way or 4-way speakers touch the grille causing rattles as well.

 

I haven't installed the grills yet, so it shouldn't be rattling against that.