Im looking to install rear speakers on my o2 s2k. is there any prewiring done at the factory or do i have to remove stock deck and run all the wires myself?
is there any available information on step by step how to install wiring ?

 

I've never seen anything leading me to believe there is. Are you trying to install the OEM rear speakers that go in the headrest?

 

There is no wiring for rear speakers in a stock AP1 ('03 and earlier car).
You'll need to add pins/wires to the car's headunit harness connector,
and run the wires back through the side sills, through the center console,
or under the carpet.
Here's a useful thread - there are no doubt many more if you use the
forum search function.

 

look at hardtopguy's site.

I think there is a plug and play harness just for this sort of thing.