best place for o2 sensors?

[Taxirod]

Hi Guys I'm new to this Lexus lark.
I'm fitting a 1 -UZFE to a London taxi, and I'm making my own headers due to clearance issues.
Ive modified SBC block huggers to fit Lexus flanges, my question is, where do, I fit the O2 sensors?
I ve been reading on here about headers but couldnt find advice on this.
Can I simply fit them where the existing wiring loom will be comfortable?

 

[Zuffen]

Fit hem after the last merge of the headers and somewhere between 9.00 and 3.00 O'clock on the pipe.

Fitting them on top of the pipe stops condensation settling in the sensor and killing it.

 

[Taxirod]

Thank you, that's what i needed to know!