The standard sensor is what is called a Narrowband sensor, which will NOT give you an accurate AF/R, you need to install a wideband one that can give an accurate reading.
An E-Manage would be adequate for a decent turbo conversion, for massive power, stand alone or a remapped OEM is the better option.
Do a search for a TechEdge 2J1, and also do some research about, open loop, closed loop, lamda sensors, MAF adn MAP sensors.
