What mods has anyone done that has been successful for both unladen performance (no trailer) and towing (max GVWR). My truck is still currently stock. Looking at mods that can be turned off while towing my 16000 lbs 5th tow hauler if need be and turned on if egts are okay. All upgrades are exceptable just looking for others that have been down the road up the hill and not melted down. BTW I live in hilly country. Not much flat land around.