question on installing head unit

[juicedcelica]

I am installing a new head unit in my car... normally I would purchase a wiring harness that crimps to the new H.U. and plug's into the factory harness.... we all know the celica has an on board amp factory... I have heard I need to un plug the amp connect the new harness to that and run longer wires between the H.U. and the amp..... is this correct???? also I have an 8 speaker system the new H.U. while having 3 pre amps only allows for 4 speaker's wired to the head unit .. how do I do this while keeping all of my speaker's????

[bme107]

I'm not sure of the best way to wire the system so you don't loose any speakers or power to them with just a new HU. Best suggestion I can give is search for "wiring harness" here and you may pick up others suggestions on how to wire it up. (you'll also find tons of flames repeating over and over there is no harness :) )