Non-OEM sub replacement for DSP car?

[Raify]

I'm pretty sure my sub is blown (item 4 here: http://www.realoem.com/bmw/showparts.do?model=BT52&mospid=47797&btnr=65_1219&hg=65&fg=20 )

Does anyone know if there's a replacement speaker that's any good / will fit? I asked BMW who quoted something between £150 and £200 for an OEM replacement (if I remember correctly)

 

[Smokin]

Not sure you can.They're Carver technology so work with the special amp. I thought my sub was blown as the bass was very muddy and muffled. They replaced one speaker (under warranty, thank goodness) but it turned out to be the amp. I am SO glad my car was still under warranty for that (I've heard $1000 US).

 

[Raify]

What's Carver tech?

You really can't just get a speaker of the same size + spec and replace the OEM one?