Problem solved !
You go in visualsettings.dat in update/update.rpf/common/data, then you need to find "emissive bits".
And there you change the values for the following lines :
and you get this :
Hi everyone, I shall want to know what to do to get the same bright effect of the Millenium Falcon's reactor like in this gameplay ?
It said in the description of this video that the youtuber only use visualV but i also use this one and i haven't this visual effect.
If someone can help me it would be nice ! 
Thanks.
@sollaholla hi, do you think it will be possible in the next update to choose the height which start the separation process of the SRB and fuel tank during the launch sequence ? This would be useful for those who want an higher orbit entry and to keep realism.
@Oskar Hi, any news on this project ?
We agree that we speak about the take-off ?
@sollaholla First of all you and your team did a realy nice work with this awesome mod. Can we change the speed/accel of the shuttle and the height which the SRB and the fuel tank leave the shuttle, all of that during the launch ? And if not, can you add an .ini file or something to set up that, maybe in a next update ?