Because the New Edge Mustang is built upon the same basic platform as the 1994-1998 SN-95, most builds take advantage of the same aftermarket parts.
Aftermarket Gearing: A simple, cost effective mod is rear gears. Changing the ratio will affect where in the RPMs your Mustang will make power. It's not a power adder, but it can make up for making your tires taller (such as meatier drag slicks). More often than not, Mustang owners change our their gears to improve raw acceleration, but you can do the opposite and have more top end speed.
Altering Tone and Flow with Exhaust Systems: The first mod most Mustang owners suggest is an exhaust system, especially if you're still equipped with the stock piping. Odds are the stock pieces are getting rusty anyway, and aftermarket options generally hold up better to the elements.
Both a horsepower and a styling mod, swapping out your exhaust pieces for higher flowing varients produce a small power gain and a throatier sound depending on the brand. If you're in it just for the sound, consider replacing just the mid-pipe.
Upgrading Your Suspension: If you're more of the corner carving type, suspension mods are a must. Coil over kits are an excellent go-to for immediate handling improvement. Some are adjustable, so you can change your ride height and further reduce body roll.
The next step from coil overs is air lift systems. Air lift are more easily adjustable so you can preserve the slammed look for shows, but you can raise the suspension a few inches for the drive home.