That's a good mod. I've seen it cure several problems. This can also be done with a Zenor diode, too. Either way, I'd say do it, it certainly wouldn't hurt anything and may help more than you would think.
There has been some documentation of a lean mode (protective fuel cutoff designed to protect the engine from prolonged high speed operation). It is triggered when the MAP pressure is above the protective set point for a programmed number of seconds. The protective trip causes the fuel injector pulse to be set to zero, shutting off fuel until the trip condition is cleared. One example would be the vehicle bucking or feel like it's missing when first getting into boost - and setting a code.
Here's how the diode gets around this. Basically, your MAP sensor reads a voltage between 0 and 5 volts. About .5v being idle and near 5v being WOT. Wiring in a Zener Diode effectively fools the computer by draining any excess voltage above it's set point (4.7v) to ground. This way the computer never sees boost and avoids problems it might have had in that situation.