I tend to agree with Merc on this one. However, I have a 2013 RS 6M and compared to the other 2 tuned Cruzes I had(Eco and LS), the RS has good spunk when using mid-grade or better gasoline. If you are using 87 or whatever the "regular" is, I could see why you feel the need/reason to tune.
First thing I suggest you do is use higher octane gas and see how it runs after a few tanks. I personally am not planning on tuning my RS and I have only had it for @ a month. Your choice. Overall what is you "end result" speed or looks?