2.25" is not the stock size. I should've taken pics of the before and afters when I redid the piping. Oh well. I have an x pipe on the way right now. I'll make sure I take a pic of the old exhaust pipe next to the 2.25" I'm going to be putting in. The largest the stock gen 1 pipe is is 2". Gen 2 stock exhaust diameter is 2.25". Be careful with going too large a diameter pipe. Too big, and you'll lose torque. You will gain on the top end though.
For simple stuff, the only things to really do are tune, intake, and exhaust. Then after that you can gear and stall. But gearing with the LS isn't as easy as removing the pumpkin, reloading, and reinstalling.