Ummm, for all practical purposes the inside area of a single 3" pipe is a wash against the total inside area of two 2.25" pipes. Exhaust tubing is approximately 1/16" wall. Analyzing it in much closer detail isn't worth the trouble, as you'll never notice any difference in power due to a small fraction of a psi difference in backpressure (where 1 whole psi is worth about 2% power). The effects of pressure pulses, resonance, and unsteady flow effects on torque are too complex to present in simplified guidelines.

Unfortunately, I can't view dodge's charts (internet filters here at work are probably the reason), but any general guidelines for selecting exhaust tubing are just that - general. Close enough in most cases, but don't try to read too much into them.


Norm

 

Thanks all!