I just got done installing the foam ones all around in my car, i left them "sealed" as in didn't cut any holes in the back, just poked tiny holes in the bottoms to feed my speaker wire through.
Like i reported ^^^ i found out one of my drivers was wired in reverse polarity, and that definitely has something to do with it, but there's a tremendous difference in sound! It probably has more to do with the phasing problem, but my other problem was that my speakers weren't sealed to the door very well, there was space for the sound to come back into the cabin, so was getting a lot of cancellation from that as well.
But def. a night and day difference with my midbass. The speakers don't extend as low anymore, but they hit the 80-100hz range with AUTHORITY, and it also made my subwoofer sound 1000000% better (maybe just 100% better) because before sometimes the notes the sub was hitting seemed like they didn't go with the song/sometimes just plain wrong, but now i know it was because the other freq's that went with those notes weren't getting played/were being cancelled out, and the midbass now gives me that 'pop' that really makes the beat stand out.
Before i liked my system, it was pretty good. But now i KNOW hands down, that this is def. the best system i've ever had in my car. I'm not crediting it all to the baffles, the wiring had a LOOOT to do with it, but if i didn't get the baffles, i would've never figured out that the wiring was wrong, so WOOT WOOT for baffles!
HAhaha.
Oh ya, the baffles make it pretty hard to get the speakers back in the holes, and put quite a bit of pressure on the screws as you're tightening them back onto the doors, so i would def. advise anyone doing them to tilt your speakers 5 deg's or so and make new holes. But overall, installation was a snap, took me about 45 minutes including a rain delay 1/2 way through.