Two types of systems are available for the Commodore V6, an older-technology mixer system and a later vapour-injection system. The mixer system is like a carburettor on a petrol engine; the vapour-injection system can be compared with fuel-injection. The latter is preferable. It offers less loss of performance, better driveability, smoother idling and less risk of backfiring. But it is more expensive, so it will take longer to recoup the cost of installing it. Many brands offer both systems. The best way to make sure you have no significant problems down the track is to choose a respected brand and have it installed by an accredited, experienced installer.