Some time ago I recall seeing something about getting operating limitations replaced with the new wording, but I can't find it. My plane was originally built in 1992, with the operating limitations from that era, including a complete prohibition on flight over densely populated areas or congested airways (what is a "congested airway", anyway?) except for takeoff and landing, any major change invalidates the airworthiness certificate instead of just going back to phase 1, and a test area 3000 miles from where I live. What is involved in getting the FAA to issue me new limitations?