What is the best way to reach o2 sensors to replace without lifting up my car and removing the rear bumper?
I removed the airbox already, but I don't think I have enough space to work on replacing the o2 sensors.
Any idea?

 

if you only want to repalce sensors and do not want to replace cats you should try to avoid taking them down, it is possible to reach those sensors only from down below, but when I was installing my x-pipe i could not unscrew my sensors - they became literally a part of a cats pipes and even after i took cats off it was quite a struggle to separate sensors from cats.

some other folks had no issues unscrewing them with a simple regular wrench, so, you can give it a try.

to not lift the car get a set of rhino plastic ramps and drive car on them, it will give you enought space to fit under it.

if you decide to take cats off - dsconnect and drop down sensors wires - you do see them now in corners as you took airbox off.