what to install amp to factory radio it has mp3 on front.. is there just a plug i can getand where ???

are you doing a 4channel amp, or just adding a subwoofer?

4 channel amp

sorry for the late replay, was out of country.....hope your still coming around the forums.

There are 2 ways you can do the amp install. Depending on the configuration of the amp, will tell you the easiest way to do it.
If the amp has a high level audio input, then the easiest way to install the amp, would be to run 2 sets of speaker leads to each door. 1 input, 1 output.
The other way would involve buying 2 line level converters and RCA's. This would be easiest at the radio. Install the line level converter into the speaker leads, then run RCA's to the amp, then run new speaker leads to each speaker