550 should have aux input for any mp3 player if not you can buy the oem ipod adapter from bmw.
2004 BMW 325i Touring SGM
2005 Suzuki GSXR 1000|1992 JDM Civic SiR RHD Black
2000 BMW M5 Avus Blue (GONE)
2002 BMW 325i Touring TVM (GONE)
1994 BMW 325i Saloon Black (GONE)