Fits nicely in stock box, use JTSherri spacers (find him on BMW forums) to avoid having to make your own. If you properly seal the subwoofer to the box, the sound is very refreshing up from either Logic7/HK or Premium HiFi (M3). No more muddy bass plateau. Use a good amp to drive it, do not attempt to use the stock BMW amp.

I bought an Alpine PDX-F4 on this site as well along with a BMW specific harness (look again in BMW forums) for an easy install and am 100% satisfied.

I bought this sub to add a little sound in my pickup, since I use it as a work truck I needed something small that wouldnt take up much space. I made a box to the specs and installed and was not impressed at all!!! The dustcap makes a horrible racket so bad to the point that I took it out, now im stuck with a $170 paper weight not happy at all dont waste your money!

I bought this for my BMW E90. I replaced my standard underseat woofers with these. They are a great upgrade but if you
Are looking for serious bass then these will probably not be
Enough for you. Run them as mid bass and stick another sub in the trunk. Apart from that these are great

For the normal listener, these speakers are great. Really, really better than they appear. Nice warm sound with a lot more punch than expected. They fit perfectly into my BMW 335. Those of you looking to help out the piss-poor factory BMW stereo, these speakers are for you. You will not believe the difference in sound quality. These speakers are a pleasant surprise.

I, however, am not the normal listener and melted mine in 6 months. I was running them with a 360 and two Arc Audio KS 900 amps bridged.

Again, for the normal listener, these are great. I am sad that I melted them because they sounded so great (just a little too weak for my bleeding ears).

This is a great compact subwoofer that can be used as a replacement of the BMW under the seat woofer. It is a direct replacement if you can get the spacers. But the Earthquake is the only choice as a direct replacement and there is no other choice in the market.

Best price for local pickup

Pretty amazing speaker. Good to fill in the gap between your components and sub. I have a Toyota 4runner and have 2 installed in the back panels and work real well for a mid-bass speaker.

Installed in a BMW 325i to replace the oem subs underneath the front seats. Not much room under the seats, but the SWS-8X fit nicely. Note to others that the box must be sealed to really enjoy all that the subs can provide.