In terms of time, its really spread around if you want to count all the preparation and research - this is what makes the difference I guess.

I must have spent at least 3 hours on the Internet, an hour looking at the (invaluable) workshop manual for my car, 45mins or so in the paintshop (not including drying time, picked it up later). Taking the interior apart was really easy since I had the manual, only took about half an hour. Getting my power cable through the firewall grommet took over an hour and lots of shouting! The simple sounding task of threading cables under the tight carpet at the back took about an hour too. Drilling holes in my tray didn't take long... connecting up my amp, sorting out and crimping my loom took a long time too as it was quite a mess and I like to take my time on the connections.

Its hard to add up the time! The installation time from getting in the car and taking out the first piece of trim to having it in its current state was from Saturday morning to Sunday afternoon. I started at about 10am on both days and didn't work in the car past sunset at around 4pm. But that gave me some time at home in the evening to fiddle around cables, crimp terminals and power tools.