I have a cylindric shaped mesh with two faces that has been extruded into the cylinder. I am using subsurf and the extruded part is naturally curved due to the subsurf. 
I need the extruded part to be almost 100% cubic and not curved. I know i am probably doing this wrong but right now i dont know any other way.
Creasing doesnt give a decent result so that is out of the question. Model it another way? Interesting but how?
Or maybe there is a solution to my problem?

I have added a screenshot to ilustrate.[![](https://i.stack.imgur.com/rll7j.png)](https://i.stack.imgur.com/rll7j.png)