The OEM  Stereo system is:

– OEM HU/iDrive powering front, rear and underseat woofers
– 4 channel output split into 6 speakers: front speakers connected in parallel with under seat woofers
– front outputs are full range, rear outputs are high passed
– (4) 4″ mids and (2) 6.5″ woofers. i3 woofers are 6×9″. No tweeters
– 15W x 4 (Professional Radio)/25W x 4 (iDrive) max power high level outputs

Stereo 2/4 harness is for use with an aftermarket 4-channel amp to power the front speakers and under seat woofers. Rear speakers are kept powered by the OEM HU/iDrive unit. No need to remove OEM HU/iDrive unit – Stereo 2/4 harness connects directly to the OEM woofer connectors.

The Stereo 2/4 harness requires an aftermarket 4ch amp with high level inputs and signal sensing, component speakers than can lower the built-in treble boost of the OEM signal or a DSP unit with signal sensing.

Stereo 2/4 harness is not applicable to Stereo systems with 2-wires at the woofer connector (pre 0909 production).

The Stereo 2/4 harness is designed for experienced DIYer’s and/or professional installers. Ordering of the Stereo 2/4 harness does not include installation support of any aftermarket equipment. Support is only limited to problems or/and warranty with the harness itself.