Whilst I am doing the wiring loom I have ordered an antigravity battery as it weighs in at 4kg (this is the biggest one they do, some are 2kg) yet has 1000 cranking amps and a voltage cut off so if you have left your lights on or leave car and battery drains it switches off automatically, you then press a button and know for certain that the car will still start. It is fine with high output alternators and is sealed so you can mount it anywhere. My friends runs them in his GT3 Rs x, Cayman R and 911 Clubsport and has never had any issues....they almost feel fake to pick up.