You have "a converter"? How did you pipe it? Dual exhaust usually means separate manifolds or headers, with 2 cats and one or two mufflers on each pipe.
One major difficulty in doing true dual exhaust lies with the O2 sensor. Short of having a single manifold or header, you have to use an O2 sensor in one side or the other. Without knowing a bit about electronics it would be difficult at best to run 2 sensors. You could likely put together a circuit that uses a differential averager or similar to create one O2 output from 2 sensors, but that's not going to be simple. So basically you're stuck for either not having true dual exhaust or else running off of an O2 sensor that's only looking at 2 cylinders.

Thomas

Sweet! And, as noted, by using a single exhaust header you don't have to muck around with the O2 sensor.
I have similar pipes on my '99 Ranger. Splits just after the cat and the chrome tips stick out just a bit right in front of the rear tires.

Thomas