The time it takes to install a new stereo system depends on the complexity of the installation. If you’re only having a deck installed, you can be in and out in one to two hours, less if your installer is competent and there are no issues. If you are having multiple components installed, this will add time. A stereo unit installs quickly, unless customizing the dash is needed. Adding amplifiers requires additional wiring, power sourcing and mounting. Replacing and/or adding speakers can require additional wiring, installation, and removal of door panels. Complex systems can take up to a day or more depending on variables like parts and unforeseen problems. For a basic install, you should be in and out in under a day.