Equal length kinds fills the gap between longtubes and shorties. Granted a large benefit from longtubes are the fact that the tubes are equal length (like the equal length shorties), which helps to scavange the cylinders better and the exhaust pulses are more tuned - but a gain is also recieved from getting the exhaust further away from heads down to the collector. Going to far will hurt torque production, and not going far enough will create too much of a restriction.

So while I feel that equal length shorties are significantly better than unequal lengths, longtubes are still king. Oh, and you can't to equal length shorties on a 4.6 - theirs no room for em. So your only options are unequal lengths on a 4.6 (which aren't really any better than stock), or longtubes. I suppose on a 5.0 if you wanna keep your exhisting h-pipe that equal lengths will be a big improvement - but Im with nomo when I say longtubes or nothing.