For what it's worth, I'm running stock torsion bars with a Darlington Bumper and a Warn 9500 winch; easily 200 pounds heavier than a stock bumper. I thought the heavy duty bars rode to rough. I'm probably riding 2-3 inches higher than stock.

BTW - that means that I have a set of HD bars somewhere in the garage.

Mine is a 1990 Amigo but I think they use the same bars.