I think the tip is low to account for air flow to keep the exhaust from curling up the rear bumper area.
The standard exhaust had a kick up then down to direct the exhaust down at an angle to keep it from curling up the back . Our ‘63 was also like that.
On my ‘66 I made the mistake of exiting straight back close to the bumper and it curled up the back and over time it messed up the chrome and discolored the paint . The other problem is exhaust coming in the interior if the weather strip leaks air.
The standard exhaust had a kick up then down to direct the exhaust down at an angle to keep it from curling up the back . Our ‘63 was also like that.
On my ‘66 I made the mistake of exiting straight back close to the bumper and it curled up the back and over time it messed up the chrome and discolored the paint . The other problem is exhaust coming in the interior if the weather strip leaks air.