i just got finished dropping a K&N filter into my cobalt ss. filter cost about 60 bucks at autozone and is model e-1009. It's a harder install to do then you would think. if anyone has any questions or needs help doing the same feel free to e-mail or pm me, i'm always glad to help. anyway, i'm not sure about performance gains, but it sure does make that supercharger sound more like a mini jet turbine. for the sound, the money was worth it.