Sorry I never updated this... was a bit rushed getting it all fixed and the straight off on a euro road trip with the X.

In the end I changed all the speakers, replaced them with Hertz drivers. I pulled out the OEM speakers, cut them out of their plastic frames and then bonded the new drivers into the OEM plastic frames. Made for a nice neat install and no cutting into the wiring loom as all the original OEM connectors were retained.

I also threw in a 10" sub (with its own amp) into the little cubby hole that the original OEM DSP sub would fit into.

I decided to keep the OEM head unit, BM54 and E53 amps in the end. I had to replace the E53 with a new (second hand) unit which was a total pain getting one that actually still worked.

The BM54 had a blown channel so it went off to Cartronics for repair and upgrade... which in itself was more a drama that i had hoped for. First time it came back I had a lot of alternator whine in the speakers. So it went back again (no cost) and they repaired it again with some different components and then it was fine.

There's a GROM unit for bluetooth audio that replaced the CD player.

Overall I'm ok with it. Its not amazing, but it sounds ok. The weak link is probably the OEM amps and/or the bluetooth streaming unit. Not really looked into it to narrow it down.

Was a LOT of work, especially replacing all the speakers into the OEM plastic frames. I'd share some pictures (I took some) but not sure there's a way to upload to this forum.