First off - credit to Kris and the folks at BoostMonkey because they discovered this: Replace the restrictive hose coupling that is in-line between the wastegate 'T' and the factory boost solenoid with a much less RESTRICTIVE 3/16" coupling available at any auto parts store - I bought two at NAPA for $2.88 each.

Here's what you'll notice due to improved airflow to the factory solenoid:
Faster boost build and very slightly higher boost levels as the solenoid now has a better physical connection to what's going on under the hood.
Boost will build a bit earlier and last a bit longer as well.

I believe all this occurs because the solenoid sees more air more quickly than stock, allowing the solenoid to work more quickly to prevent dumping boost through the wastegate (which opens at 8 pounds)

Prior to this mod, I NEVER saw second gear boost approaching 14 pounds (maybe 10-11 at best) - Now my car peaks momentarily at 14 pounds plus, and settles between 12 and 13 pounds in second gear - plus it holds boost a bit longer.

Subjectively, this feels comparable to running a stock WRX on 93 octane vs. 91. BTW, my WRX is stock except for the grounding mod. If you want pictures of what and where this piece is, look at the BoostMonkey website under 'install'.

Again, thanks to Kris for figuring out something we can all benefit from.

Update to:

http://www.scoobymods.com/forums/showthread.php?s=&threadid=542

Officially my first WRX mod. These additional photos may or may not help. PepBoys sells the couplings for $1.99 for two.

Closer view.

Picture with hoses loosened from restrictor slightly.

Inside diameter difference of restrictor vs. the 3/16" coupling.