Replaced the original irritating chime of the instrument cluster with a gong from E46/E39/E38.
Both the E85 speaker and the gong are operated by ground signal, so it just a matter of disconnecting the negative leg (pin) of the speaker and forwarding this signal to T2 pin of the gong with an additional wire. The gong itself also needs 12V power and ground wiring, but this was already present in my 2003 E85.