08 sentra 2.0L exhaust system

Look up Stillen... they have one for the 2.0L

You know, a full cat-back exhaust system on a stock motor may not be what you really want. If you just want a bit beefier of an exhaust note, I'd suggest a performance muffler instead, since widening the pipe starting at the catalytic converter will actually decrease the power available to you lower in the RPM range (where you're going to be doing most of your daily driving anyways). Unless your drag-racing, or tend to drive with your right foot firmly planted on the floor, or have installed some sort of forced-induction (turbo, supercharger), I'd stick to an aftermarket muffler instead.