My experience:

Rip and replace.

I took all the factory stuff out except the speaker wires. Used those to connect to an 8 channel DSP amp and a measly little 500w amp for the sub. The secret is in programming the amp. Set each speaker's distance to the driver's ear. Set electronic crossovers to the limits on what each speaker can actually produce (and still sound good). Then, fill the bottom frequecies with a sub. If you do it well and aren't beholden to ridiculous competition level sound EQ goals, You will be very happy. It's no stoplight stunner. It will *roll* with the windows up at speed. Her little teeny bopper friends like it when she drives the E53 instead of her E82.

Speaking of her E82, I recently replaced the stock speakers with BavSound. The result was underwhelming. This weekend, I replaced her OE 676 HiFi amp with an old school UP7BMW unit. Plug and play except for a mounting harness that wasn't at all what her little 128 needed. But, boy, oh boy. Set the response times and the crossovers and her lil 128 is ready for college in August!

But yes. I will add a sub this Christmas on her lil 128. As good as it sounds. Baby girl's E82 *needs* some depth.

__________________