What Modification Do You Regret?

Not a Mopar and not my car but back in 1986 my friend bought a low mileage all original 1973 Mach 1 Mustang. After driving it a few months he decided to make a bracket car out of it. I begged him not too, but he took out the cutting wheel and took out every wire in the car, cut the dash frame and supports out, and generally tore the car apart, only to sell it a few months later as a parts car!