The Names Josh and I have a 2011 Malibu

Hey everyone, hopefully some will reply.
My name is Josh, I am 17, and recently bought a 2011 Malibu LT in Black Granite, and yes I make payments on the car myself, I am not a spoiled young kind against any stigma that may be made against someone who is as young as me and owning a car. I love the car and I could not be any more happy with it, although I am still breaking it in and am going really easy on it. I am really ignorant to this site as of now and need to learn better how to navigate to creating my own thread as I have my own questions. I will ask my first question in the new member introduction because I am anxious to find out how to make my own general thread. I want to put a one in and two out muffler on my LT an do duals out the back, of course it is a 4 cylinder. I found a valence for a 2009 LTZ with duals and is only 30 some odd dollars on partsgeek.com however I dont know if a 2009 valence will fit but that price is better to others I have found. Also Im not sure if partsgeek is a SH&%$# Website. My questions is will a 2009 valence fit? I believe the body styles between 09 and 11 are the same so it shouldn't matter. This would save me about 70 dollars compared to other sites with the dual valence. I dont want it to be raspy, just something alittle less restrictive, also will this hurt the gas mileage/ I dont want to mess up the back pressure but I figure if I used something still medium in the restriction category it won't mess up restriction too bad.
Thanks,
Josh
http://www.partsgeek.com/catalog/2009/chevrolet/malibu/body_mechanical_-ar-_trim/valance_panel.html