The owner of this heavily modified 540i contacted us initially to enquire about retroftting the factory BMW navigation system, but when he was told the price, he asked for some alternatives! We fitted the latest Alpine IVA-W200Ri double DIN DVd touchscreen navigation system, which involved some pretty serious modifications to the air conditioning system as BMWs can't normally accept a double DIN unit. The audio system is based around a DLS CA41 4 channel amplifier, running some DLS Reference front speakers, and a discreet OA10 free air subwoofer in the boot. The bespoke facia panel around the head unit was veneered with burr walnut to match the factory trim.