what could be added in my system ?
Well... there is this section called "Modules" on this Modulargrid.net website, it's full with modules there (thousands of them), any module you don't have yet and that from an HP size perspective fits, is a good candidate, no?
Good luck with choosing a nice module and kind regards, Garfield Modular.
P.S.: Or you specify your question a bit more accurately plus some background information on your shown rack here (do you have that already, is that the last bit of space left, that kind of info) and perhaps we are able to answer your question more specifically ;-)
actually that my system and i'm on my way to ending it up soon
my question relate more for what sort of modules could be missing (logic modules ? VCAs ? mixer ? ) i wanted people's opinion
If the above rack is a planned rack but not yet an existing rack then my advice is to don't fill up the rack completely in one go. Start with some basic components first from what you have chosen (i.e. a few oscillators, LFOs, EGs, filters and VCAs). Get some experience with them and with that gained experience re-adjust your planning and thoughts and then add a few modules accordingly to that.
It's important to keep some reserved rack space free for future module extensions otherwise you are going to need soon another rack. I think rack-size-wise your rack size is okay but just don't start with a big number of modules in one go.
Good luck with the planning of your rack and kind regards, Garfield.