I note the invidia auspec dp has the o2 sensor before the cat whereas every other dp and the stock dp seem to be the other way around. Is there any problem with the sensor before the cat? Does this sensor affect afr and if so wouldnt this be thrown out as I would have thought there is a lot more o2 before the cat than after where i assume the ecu thinks its located?

Is this something the tuner can work around or is this problematic? All seems fine after my tune but I am just curious about whether there are any adverse impacts that might not have any obvious symptoms.