Originally Posted by Halston Pitman

If you do want to remove head unit or amp in the DSP system you will have to 100% start from scratch.

You will need a new head unit, amplifier, speakers with crossovers and subwoofer if you want to replace the OEM system. For the cost our Stage 1 + Subwoofer and an iPod kit or satellite radio ends up being substantially cheaper and sounds quite good. Many x5world/xoutpost members here have this setup and love it!

If you have any additional questions just let me know!