D2 v8 missing 02 sensors

Hi all
Went to replace all 4 lambda sensors on my 2001 v8 d2, and found their weren't any post cat sensors at all..
Hasn't been done in the 5 years I've had it, so not sure what the thinking was when done.
My question is though, if I replaced the exhaust, and cats. Would the harness have had to have some sort of bypass done?
The connectors are still there, but would they work?

I've replaced the camshaft position sensor today, which restored a fair bit of power, and sorted poor economy.
Seems ok atm, but has had major emissions issues at the last 2 mots.
Any advice would be appreciated.
My plan was to get the thing going again, then build it up a bit for some off reading.
But following the good advice of getting the mechanicals sound 1st seems to be going on for ever....
Thanks in advance
Matt

You being in UK it's normal to have 2 sensors but the harness is the same for all and the ECU is programmed for each that setup... if it wasnt so it should have been on "open loop" default and run like sh*t

Awesome, one less thing to worry about
Thanks once again..