Well, 100K is pretty good for a 97.
There is no performance aftermarket for that Aurora 4.0. Bolt ons from manufacturers are...well, non existant. You can do things on your own. Typical mods are airbox gut/K&N, aftermarket exhausts, electrical grounding kits, 80mm TB'*, 2nd Aurora gen injectors and STS strut tower braces.
The 32V DOHC is a decent mill, suits me, even power distribution, and a decent 250HP/260 tq. With the mods above, 280 bhp is achievable.
Common breaks, FPR, hub bearings, multifuncition switch and some of the earlier 4.0s leaked from the oil pan. By 97-99 that problem was fixed. The 97 did get upgrade brakes, compass in the mirror and tilt down mirrors.
Good luck with your choice.
Diamond White Classic Aurora - Back on the Road
Galaxy Silver Grand Prix GTP CompG - Soon to be mothballed