Question about mechanical cel fix for Invidia one piece downpipe

[fengzhaoxi]

I just got my Invidia one piece catless downpipe. There are two O2 Sensor locations: one is on the downpipe section and anther one is on the testpipe section. For the test pipe section, I am sure that I need the mechanical cel fix (either made it by myself or buy it). But for the downpipe section, do I also need the mechanical cel fix too?
Thanks for helping~

[solarevo]

i just used the spark plug spacers, drill one out and leave the other the way it is

[UT_EvoX]

To actually answer your question, you only need the CEL fix on the 2ndary/rear O2 sensor. The front one goes directly into the exhaust stream as it did stock.