I have a 24' travel trailer. I pulled it ok with my 1996 GMC that got totaled. I bought a f 150 sport 2wd with 4.6. Empty, the 4.6 feels as strong as my 96 with 350. I know the 4.6 is a small engine. Would new exhaust help much for towing? THANKS!!!

 

Replacing the muffler with a straight through type in the stock pipe size would help. Duals would not help, in fact duals will cost you low end torque. Keep the pipe size smaller yet free flowing to maximize horsepower without costing low end torque.

 

You might also consider a lower rear gear ratio.
Look at what you have.
It likely is a 3:55 but a 3:73 or 4:10 would pull better over any exhaust changes.
Gears from any year 8.8 will interchange to make it fairly inexpensive.
Lower gear ratio will allow the motor to get into a good torque production RPM faster from a stop and keep it there more of the time while towing.
2000 rpm is the majic number where the torque 'comes' on from the cams and continues to build as it approches 3000+.
Once gear ratio is changed the speedo won't read correct unless corrected.
Good luck.