well, this is what i would do...
id get a short ram and when it is time for the factory check-up, id slap in the oem intake so that they wont give you any bullshit.

the short ram should be pretty easy to install and you dont have to worry about hydrolocking the engine.

spark plugs wont void the warranty, but are changed on the basic tune-up.
but if you are going to upgrade the sparkplugs, just make sure you have them for the right year and model.