I've took the time to re-do this personal project. I've improved the unwrap adding symmetry for some parts to improve the uvw space. I've used also weighed face normals to improve the bake in some areas.
I've also reworked all the materials in painter and created a new studio in Marmoset in order to achieve nicer results on the render.
Thanks to my colleagues for his advise, always helpful.
I hope you like it!