A lot of the speakers I'm seeing are "over sized 6.5" or 6.75. Pioneer even states it as "Improved Fit on GM Oversized 6-1/2" Applications"

I plan on dremeling out the stock non-pioneer speaker brackets and adding a speaker. Would 6.75 fit without much hassle? I haven't been inside Cobalt door panels yet. I'm finding a ton of good speakers in this size.

 

lol id be surprised if the pioneers are even 6.5... personally i would stay far away from aftermarket pioneer speakers. far far away