The speakers are specifically designed to work with your system for ease of installation and proper connection. This does not allow the use of different speakers or the use of your speakers with different systems, which would cause improper matching of electronics and could cause distorted sound or damage to the equipment.
Speaker wires are set to a length that should accommodate conventional installation and provide excellent sound. Lengthening wires not only voids the warranty but can result in loss of sound quality and risk of equipment damage.