I wanted more from my factory radio but didn't want to go all out and replace the entire system. I upgraded the factory speakers to Polk db571s then searched for the smallest 4-channel amp I could find. I ended up with this Alpine amp. It takes speaker level inputs and amplifies them. Plain and simple.
It is designed as a plug and play add on for non-amplified Alpine systems. It plugs into an Alpine head unit and the factory harness plugs into it. After doing some research, I found out that people are installing these on non-Alpine systems too. You can find its specs all over the web.
The wiring harness is this http://www.redtagcellular.com/produc...s-03%252b.html
adapter for some bluetooth thing. If you plug those two small connectors into the big connector, it's basically a pass-through cable. This allowed me to add the amp inline without cutting the factory wire harness.
I cut off the Alpine connectors, and cut the speaker wires (8 wires for 4 channels), constant 12v (yellow), switched 12v (red) and ground (black). Then I soldered and heat shrink wrapped the lines.
When I was done, I had the Alpine amp with a Ford connector on the ends. The bundle of wires included 4 speakers channels, constant 12v, switched 12v and ground -- all in one neat package. The only snag I ran into was the switched 12v (red wire) wasn't getting anything when you turn the ignition key. After a little spark chasing, I ended up using the orange with black stripe coming from the factory wiring harness and connected that to the blue with white stripe going into the amp.The Alpine amp had a bunch of other wires I didn't need. I just bundled them with a wire tie.
The wires on the amp were maybe 2-3 feet long on each side so everything reached the back of the factory head unit with the amp tucked behind this panel. It fit snugly so I didn't even have to bolt it in or anything. I could've tucked the amp just under the factory radio, behind the radio controls. There was plenty of room but you have to push some wiring harnesses around. I didn't want to bother with that. Besides, that space at the bottom of the radio stack is prefect.
This is what it looked like before and after the install. Nothing is visible. Nothing under the seats. Nothing on the back wall of the cab. Nothing under the hood.
As far as sound quality goes, it's a huge improvement over stock. It's not earth shaking like the $500-1000 upgrades but for my tired old ears, it's heavenly.