"Upgraded" the 2g blow-off valve to the 1g version, and added an upper intercooler pipe from RRE to remove the restriction of the stock pipe (and to avoid buying an adapter for the 1g BOV). Also installed a K&N FIPK, to let the engine breathe a little better. Initial tests indicate that we're now pushing upwards of 17 PSI, which translates into a significantly more violent launch; the car now pulls down to the ground and leans back at WOT. Thanks to Gary Bechtold for letting me give some of the parts from his old 2g a good home.
A note to the curious: yes, the K&N filter was used (about 15000 miles worth), and yes, it cleaned up like it was brand new. Nice filters.
Later: removed the restriction on the waste gate solenoid, resulting in a slight boost improvement. A quick test launch resulted in 21 PSI peaking boost levels when shifting, averaging about 17-19 PSI.