I started out years ago towing our 7,000 lb trailer with my old chevy 2500 with the 350. I tow mostly in the Sierra and Rocky Mts. I hated the way I had to slow down to 45 mph going up the grades. So ...
If you don't let the V10 sing (rpm's) you aren't giving it a fair chance to show you its capability. I towed my TT in sig all through the south east mountains with mines and the steepest passes required full throttle and all 10 cylinders singing but it kept up pace. It isn't quiet by no means but even diesel make some noise when pushed hard.