Big Red Car's dump-pipe is conical for the first 2/3 or so, it bell-shapes out to a fairly straight bit of pipe for the last third (where the wastegate output joins the exhaust).
Now ... I'm fitting an O2 sensor soon, and I'm wondering whether it will read correctly if I fit it out where the pipe's cylindrical? If I fit it up closer to the turbo, it forces more gas to flow past the sensor; but then the sensor is more of an exhaust obstruction (plus I thought heat became potentially more of an issue closer to the turbo?).
Can anyone tell me whether it's better or worse to fit the sensor after the conical section of the dump-pipe? Would my guess be true, in that there's only exhaust-gas in the dump-pipe anyway, so the sensor won't be reading too inaccurately even if it doesn't sample heaps of gases?