I saw the other day a 2005 corolla in dash CD changer and a JBL seperate amp that comes in the 2005s. I was wonering if anyone has tried to put one of these in a 2004? It looks like the plug is the same, im just not sure about the seperate amp.

I think the harness in the dash would mesh up pretty well, the only thing missing would be where the wiring harness incorpoates the amp. You could probably figure out which wires coming off the JBL changer are the remote lead and then then use speaker level inputs to the amp unless it also has RCA jacks.

Did you notice any MPG differences when you put those 17" Scion wheels on? Change in acceleration?