1999 montero sport upgrade

I did a search but have not yet found anything concerning my issue. i installed a sony hu to my exsisting system and discovered that it has a factory amp(infinity system). i have been told a complete rewire is necessary or amp by-pass. can someone tell me my best option. oh and i was told also that my speakers may be 2ohm and thay could posssibly damage my hu. where is amp located?

For a '97 under the right rear seat. I imagine yours would be the same place. Also they make a factor amp integration harness. Around $25-30. Metra harness 70-7003. Allows you to use the factory dins on the amp to RCAs inputs. You would simply run RCAs from the deck output to this harness. No need to worry about the ohm of the speakers with this. You will only be supplying signal from the deck via the RCAs to the factory amp.