The 3.0 V6 is pretty much a economy based v6 Ranger. I used to own a 1994 Ford Ranger with a 3.0 v6. It had a fairly loud exhaust (not as loud as other engines). I wonder how much more torque is added when you place a after market exhaust to a 3.0 v6. How much torque does your 3.0 v6 Ranger make with a after market exhaust?

 

Not a lot. Opening the exhaust helps top end power in most cases. The gains are less at lower revs. What you are doing is relieving pumping losses by making it easier for the engine to expel the exhaust. At lower revs and partial throttle, the open exhaust isn't helping much. Over 4500 rpms, it may help a little.
Let's say it's worth 5 HP. At 4500 RPM, 5 HP is worth about 6 ft-lbs or torque. At 5252 rpm, HP and torque are equal, so up or down from there the gains are similar.

I'm not sure you will find actual dyno results here testing the loud muffler theories.

If you have a series of 0 to 60 or 1/4 mile times, and can duplicate the runs with and without the loud pipes you will also find your answer.

And of course, there is the butt dyno....