You are not limited to just slip on. Depending on how emissions works in TN you might be fine. As long as you run a tune or akra-r to remove the CEL light for no cats you will be fine.
In Chicago, there is no sniffer test, but they hook up to the OBDII port to check if you have any lights on. If it is the same you will be fine.
Here is what I am running, the full Evolve E-Tronic Exhaust
I love this exhaust because it allows you to have two different exhaust notes for the price of one.
But there are plenty of exhaust you can purchase to make the sound change, for example the Eisenmann race which I know is really loud if that is what you are looking to do without having to remove your primary cats