Not a significant difference all the dual exhaust does is cut back pressure ergo the louder sound
about 5 - 10 hp
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 )
200 horsepower ( 215 horsepower with dual exhaust )
The advantages of having dual exhaust, if it is a true dual exhaust, include increased gas mileage, cooler engine temperature, and more engine horsepower. However, if it is not a true dual exhaust, it doesn't matter how many exhaust ports there are, there will be no advantage.
If that's a 360 - 4 barrel ( 170 horsepower / 160 horsepower in California ) Actually the E58 360 4 barrel with dual exhaust was rated at 195 HP! I own one!
Yes it will. Not a huge difference, but if you put a nice dual exhaust system behind them, including a balance pipe, you will increase your horsepower and your mileage. You might expect to see 1-2 mpg.
Dual exhaust and P71 210. Single exhaust 190
For a ( 2002 ) Mercury Grand Marquis : 220 horsepower ( 235 horsepower with dual exhaust )
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 )
165
According to the 1998 Mercury Grand Marquis Owner Guide : Single exhaust ( 200 horsepower ) Dual exhaust ( 215 )