Wide band sensor

Where would a wide band sensor be installed or placed. So like the narrow band sensors are behind the cats. Would the wide band be before the cats. So lets say right off the header before the cats would that be good place for wide band sensor or sensors. Like the narrow band there are 2 sensors would i need 2 wide bands or would one be efficient. Ill be tuning my 2011 Silverado 2500hd 6.0 liter engine does factory ECU have wide band sensor or sensors. If not will factory ECU except wide band to help with my tuning. If ECU wont except wide band is there another way to use wide band to help with my tuning. Sorry if my questions are a little confusing do my best but not always the best at asking

questions lol!!

Thanks

Josh

Wideband/AFR are most commonly positioned after the turbo ontop of the downpipe and are easily spotted on inspection. I can only speak from Experience but i use AEM AFR hooked up to a Link ECU. My guess is you will need an aftermarket ECU or will need to check with your manufacturer whether the ECU Supports this, it will need to be a sophisticated ECU to do this from stock.