Modeling /Subdivision Subsurf question

[Karmaterrorᵁᴷ]

Im making a little spaceship and im working with a subdivision subsurf modifier and mirror. I want to keep that in place for tweaking the hull, but i want to add cylinders for little tubes and stuff.

When I add them the subsurf affects them as well so they spawn in like funky spheres. Can i keep them as part of the object so i keep mirror, but not have subsurf affect those parts?

[Stretchyf]

Subsurf cannot be applied to only part of an object - it works for the whole object. But you can play with the creases so that subdivisions don't round off things they shouldn't.

As far as I can see you have two ways to go:
1. Use fairly low poly cylinders so they can benefit from subdivisions. Make edges around their caps 100% Crease.
2. Separate them, cylinders, into another object that doesn't have a Subdivision surface modifier.

[The Renderer]

Unless you have a really good reason to do otherwise, you should do #2 of Stretchyf's suggestions. Trying to make those little addons part of the main model will only lead to problems, from the one you describe to UV unwrapping to making it difficult to move/change them later. Hint: If you seperate the objects with the P menu, you will keep the modifier, so you won't even have to re-set up the mirror modifier for the cylinders.

If you do #1 consider using support loops instead of creases since you probably would have to bring up subdivisions to a pretty high level to make those creases work for something like a cylinder. Depends on your geometry and on how closely you want to look at them, though.

[Karmaterrorᵁᴷ]

Thanks so much guys :)