air fuel ratio guage help

I have a 2004 chevy cav with the
ECOTEC 2.2L engine. I have extensive
mods including a turbo and fuel system.
I was wondering if anyone new
exactly which wire you tap into
for the signal wire to your o2 sensor
in order to install a air fuel ratio
guage. I'm going with autometer brand
if it helps any. Also where is the best place to
tap into this wire. Anyone with information
feel free to email me. Thank you all for the
help in advance.