I had similar questions a few weeks back concerning my srt6 and from what I discovered aside from the dual CAI looking cooler than the single you are not going to get any real benefit from it.The dual kit claims insane cfm flow rates ,more in my opinion than even the srt6 engine needs.If a cool looking intake setup is what you want go for the dual setup but the single kit is plenty good performance wise especially for an na car.As far as the exhaust goes from what I've read exhaust mods don't give much of a performance upgrade to these cars its more of an exhaust note preference.From what I've heard on posted videos I personally like the resonator delete with the megan muffler its not too loud yet gives it a nice deeper tone.To me the magnaflow just sounded too loud and droning but again thats just my opinion its all about what you like I like the thoaty sound the megan gives and people that own them say they dont make you deaf on the highway when cruising.Hope this helps you decide.