1968 Chrysler 300 - Stock with Glasspack Muffler

I posted a video of starting the 300 about a year ago, but now that we have fresh gas and some tune into the car I wanted to post another. The previous owner has left the car stock except for the installation of a glasspack muffler on the single stock exhaust. I will be using this video as a reference point in the future if I decide to install any exhaust modifications. Which leads me to my next point: SHOULD I install any modifications to the car and WHAT?! I have some ideas, but I would be interested