After a few nights of reflection, it's gone, I embark on the adventure.
I will post here as I progress, so that you can follow my adventure step by step. I'll try to put pictures, it's still more meaningful than a long speech.

So I spent the first 2 steps, which consisted in finding the best location for the reactor, and finding or connecting the pantonized air intake.

For the reactor, in my opinion the easiest is to put it in place of the catalytic converter. The downside is that it is about 1m from the exhaust pipes, but the advantage is that it is very easy to access when the car is on the bridge, and above all, you only need to unscrew 3 bolts to disassemble it…. Anyway I would have had trouble putting the reactor before, because there is very little space.

So I went to a junkyard, and I managed to find almost the same catalyst, there is just the tube which comes out of the catalyst and which will plug 1m further into the silencer which is too long, but it will be easy to cut!

I will therefore be able to decapitate the catalyst, transfer the honeycomb, and I will have all the space necessary to place the reactor. In terms of temperature, even if I am a little far from the exhaust pipes, I think that it should still go up quite high since anyway a catalyst needs a high temperature to work. If that's not enough, I'll isolate ...

For the air intake on the intake, I realize that it will be a breeze. Indeed, I have 2 air inlets on the manifold. The first is the one whose opening is modified by the throttle, itself driven by the accelerator pedal.

And the 2nd, much smaller, is the one for slow motion. There is a servomotor controlled by the computer which manages this air intake, to adjust the idle air flow.
This means that the first air intake is completely closed at idle.

So I am going to make my air inlet on the inlet intended for idling, because the hose which connects the manifold to the filter is very easy to access, and its internal diameter is about 10mm. So I will not need to make a venturi, because it already sucks strongly.

I can even dream a little and tell me the Pantone system also work in slow motion !! Smile

Now, the 3rd step is the reactor itself. I did 2 DIY stores, I found a 20mm diameter steel tube, 1.25mm thick. The internal diameter is therefore 17.5mm.
By cons I have not found what to do with the rod of the reactor. They did not have a 15mm diameter steel bar. I think this is the diameter I need, because it would make a space between the rod and the reactor of 1.25mm.

So I haven't bought the tube yet, because I have to find something to do with the rod first.
In any case I think I will stay on steel, because working with stainless steel is still not easy.