CFast,
The operation and HP torque gains are identical on either style box. The only difference is the connection method. When the trucks were newer folks didn't want to break the seal at the injection pump connection to install a box for warranty concerns, so a connection was designed to use the data port on the trucks wiring harness so the pump connection was not disturbed. Now that the trucks have some miles on them most of them are out of warranty so it doesn't really matter. Either way you connect it you get the same performance, we only stock the van Aakens that connect to the data port and the MAP sensor, no reason to have both as they do the same thing. Call us if you have any questions.
Mark @ DPPI