What Modification Do You Regret?

I bought an original 68 gts 340/auto dart. It wasn't perfect but rust free and definately a driver, less engine. A friend got it from us andmade it into a bracket car that ran at Carlsbad raceway in the 80's He cut the inner doors frames out and the supports from behind the back seat. well we traded back for it and took the engine and trans out. This is about 1985 and no one wanted it so we litterally cut it into pieces and sold it for scrap! Kills me now.