I read sometimes that tris / n-gons are not so good for texturing and quads are better. But yeah that's the thing, I don't know yet a lot about texturing. So I will try it out with the render engine.
And yes the export is very good in MoI. The model in C4D is exactly like the model in MoI with all the correct shading in most cases:)

Hi Nikita,

re:
> How can I close that hole and how I can boolean the cylinders from the main object?

I've attached a version here that has the hole patched up. There is a little edge in there that is making things a bit difficult. I ended up untrimming the surface above the hole and retrimming it with a line that matched up to the little edge better, then i was able to join together the little edge with its longer neighbor and use Construct > Network to make a filling piece.

- Michael

Hi Nikita,

re:
> I read sometimes that tris / n-gons are not so good for texturing and quads are better.

There are some programs that do not have very good support for n-gons. If that's the case then yes for that particular program this might be true but it's not applicable to programs that handle n-gons well.

- Michael

Thank you very much for having a look and fixing it and the explanation, even though I couldn't recreate the fix myself, but yeah I will just be more careful and thoughtful about every step I do in MoI to not come into issues like that later.

And also I found out some ways to align the texture to the exported MoI3D model in Octane. Thanks!