Please recommend a small free-air sub for my BMW
 

Hey Guys,

I recently acquired a 2001 BMW 330i with the Harmon Kardon system, and was thinking about just adding my deck (Alpine CDA 9835) and an amp with two small free-air subs. The factory system has two 8" subs in the rear deck, and I would like to maintain the factory appearance. I have a US Amps US400 which should be able to power the subs.

I am still undecided as to whether or not I want to install my Focal Utopia 165W's in the front (powered by a PPI Art Ax400), but as of right now, I just want to try the facotry system with the Alpine deck and some nice (but not necessarily huge power) subs.

What do you guys recommend? Should I go with 8" free-air subs in the rear deck? I want them to have good SQL, and a little bit of punch.

Thanks,
Bryan

I don´t thing free air sub are the solution, you may use a good 12 in a vented box, or custom fiber glass box, vented too. If you are thinking to change the head unit, then use a 4 channels amp. Two channels to the focal set, and to channels to the 12 single 4 ohm voice coil. Let the rear speakers to the alpine unit direct. Is a good idea to insonorise the doors with dynamat.

Parts Express:Dayton QT210-4 8" Quatro Subwoofer 4 Ohm

High QTS, reasonably low FS, and respectable xmax should make these a good candidate for an IB install.