I have been into cars for over half my life. After doing modifications "just because", I now prefer to do simple modifications just for looks (like rims) and mechanical modifications just to make a system or component work better.
For examole, in my 71 Pinto, I have gone to Pertronix electronic ignition and a Mallory coil. This is simply to improve driveability and gas mileage. Points ignition systems are ancient outdated technology. Similarly, I am going to find some more comfortable seats that give me more leg room. I am 6'4" so I need all the room possible in a Pinto, and a previous owner already swapped out the factory seats.
If I know how to modify the gas tank to be safer, I would. My Pinto has the Ford retrofit, but i am still a bit nervous about it.
Basically, I feel if it ain't broke, don't fix it, unless you can improve it. Whith that philosophy, I am going to do some minor body mods to improve aerodynamics, some engine mods to improve fuel efficiency, some interior mods for more comfort and better instrumentatio n.