Dual is usually louder due to less back pressure. The amount it is louder depends on how it's built.
Not a significant difference all the dual exhaust does is cut back pressure ergo the louder sound
Dual exhaust and P71 210. Single exhaust 190
For a 1998 Lincoln Town Car : It depends on which state it is sold in and if it is single or dual exhaust Single exhaust ( 200 or 205 horsepower ) Dual exhaust ( 215 or 220 horsepower )
According to the 1998 Mercury Grand Marquis Owner Guide : Single exhaust ( 200 horsepower ) Dual exhaust ( 215 )
According to the 1998 Lincoln Town Car Owner Guide : For the vehicles sold in California , New York , Massachusetts , Connecticut ( single exhaust 200 horsepower / dual exhaust 215 horsepower ) Outside of those four states mentioned above : ( single exhaust 205 horsepower / dual exhaust 220 horsepower )
According to the 1999 Ford Crown Victoria Owner Guide : With single exhaust ( 200 horsepower ) With dual exhaust ( 215 horsepower )
150 with single exhaust. 160 with dual
For a 2000 Ford Crown Victoria : With single exhaust ( 200 horsepower ) With dual exhaust ( 215 horsepower ) According to my Consumer Guide book
A 1994 Grand Marquis came from the factory with 190 horsepower (if equipped with only a single exhaust setup) or 210 (if equipped with a dual exhaust setup).
A cheaper option for dual exhaust without making it a true dual exhaust from the exhaust manifold/headers. Not much performance gained just appearance.
For a 1992 Ford Crown Victoria , 4.6 liter V8 engine : Base and LX ( that has single exhaust ) ( 190 horsepower ) Touring ( that has dual exhaust ) ( 210 horsepower )
The 1991-1997 Lincoln Town Car with the standard 4.6L engine has 210 horsepower if it has dual exhaust. Otherwise, the power is about 190 horsepower with the single exhaust.