My 2004 6-cyl F-150 pulled a 19ft Antigua from TN to Alaska and back, New England and back (twice), Louisiana and back, and Florida and back plus short trips and a 24ft Passport Ultralite to Calif and back and is still going strong at 160,000 miles. I never felt like it was really straining in the mountains and did not have any mechanical problems until last year(busted intake gasket) and minor transmission problem this year. Average 9-10 mpg towing. That being said, I am looking for replacement TV and will probably get 8 cyl, or 6 cyl with Eco boost or Hemi. Since I want something I can carry my kayaks on and have more passenger room, I am looking at Expedition, Yukon or Durango, etc.