S40 2003 replace Hu-605

[catalax]

Hi,

This is my first time when i write here.
Today I choose to replace my old HU-605 with an aftermarket new stereo.
Beside speakers wires (8), the new stereo has only 4 wires more (red ACC - Power lead, yellow - battery lead 15A, blak - Ground lead, blue - motor antena).
But my old connector has many more wires.

I downloaded from internet the radio diagarm (see attachment) and I'm still confused.
Ex: inside the car I have one thin red wire and one thick orange wire (although I din't find any orange on schema just reds), one thin black wire and one thick black.
The new stereo has one black and one red by the same thickness...

Could someone help me with some indications?