I Upgraded Mine Using A 4awg. I Do It On All My Cars.. As Most German Cars The Ground In It Is Weak. It Only Takes About 10 Min To Upgrade It.. Just Buy A 16inch Piece Of 4awg Wire And Some Ring Terminals, Crimp The Rings To Each End Of Wire, The Attach One End To Neg On Batt And The Other To Chassis Ground.. Make Sure Its A Good Ground Location If Needed Scrape The Paint Off Before Grounding. Then If You Had To Scrape I Sudgest To Spray Some Rust Stopper To Avoid Any Rust Or Build Up On The Contact Point.... I Go Above And Beyond On My Cars Being That I Do Wiring For A Living. So I Do A Few More Key Points.. I Make One Going From The Engine Block To Ground. And Also The One On My Altinator. This Will Cover Most Of The Charging System In The Car. You Will Notice Less Dim Lights When Driving At Night With A/c On When The Compressor Kicks On.. Hope This Helps You Any Other Questions Let Me Know...