the mirror in my RX7 was like that when i had 2 12" IMPP's, and 2 12" Kicker Comps in the back of my hatch and 1000w pushing them... my outside mirrors rattled/vibrated just as much as my rearview.

My glass never broke, but it would bow in and out as much as 1/2", same with the front windsheild but that wasnt sitting on a weather strip like the rear. my wipers would bounce up and down quite a bit. even my speedometer needle would jump up and down when i was at a stop. now thats Madd bass yo.

I used to be into that stuff pretty big, i was actually in the process of making a custom box to take up the whole rear compartment my RX7, from the back of my front seats to the rear wall. gonna have those 4 12's in it, and then 2 JL 15's in it and 1600W total power... i had it all screwed and glued together, just needed to put the interior baffles and top on it and itd be done. but then i figured out that i would have been WAAAAY slow and dragging my ass around town... so i gave up on that project.