This vehicle range had 3 different shape radio's as standard...

Standard 2004-2008 (171x90mm) | Vehicles with the standard audio system require the standard ISO lead. Vehicles with the Boston Acoustics amplified system require the amp bypass or retention lead. Boston Acoustics systems can be identified by the logo on the tweeter housing.

Navigation 6 Disc Radio (209x130mm) | This system normally had the Boston Acoustics amplified system and a rear seat entertainment package (RSE). You can bypass or retain the amplifier on the fitment. A double DIN conversion would be recommended on this.

MyGIG NTG4 REW Navigation (204x97mm) | Vehicles with the Boston Acoustics amplified system require the amp bypass or retention lead. Boston Acoustics systems can be identified by the logo on the tweeter housing. There was also a non-navigation basic model in the same shape as this, which was not amplifed and on ISO connections.