decatting my car and the o2 sensor

[Ballsy_Sport]

i am wanting to decat my car and i know i need a o2 sim to stop the engine management light coming on but i dont know how the o2 sim will work?

at the moment with the standard cat on my car where are the sensors connected to and how are they connected?

there aren't any off the shelf decats available for the ep2 so i need to get one made, so what will they need to do to be able to plug in the o2 sim?

will the o2 sim need to plug straight in to the decat or something else?

cheers.