I like to know if anybody knows whats better ,I was getting ready too order the 140087 and found out that the 140086 will keep some back pressure .I thought duals was always better but I gues these knew beast 5.4 are differnt .THANKS for your input

 

more back pressure gives you more torque at a lower rpm. Less back pressure give you more horsepower at a higher rpm. If you tow a trailer get the SO if you just wanna go fast get the DO. Will you really be able to tell a difference? Probably not.