Still kicking this around.... Here are some options for the Gauge install that are available from Advanced Auto Parts...
These should provide a straight-forward way to get the hard plastic tubing for the gauge into the 11/32" intake hose with very little plumbing.
3/8" X 3/8" X 1/4" Vacuum "T" Vacu-Tite!
Dorman 494-015 Package number 47345
Advance Auto Parts SKU 5019664 $1.99
1/8" X 7/32 Soft Vacuum Connector Vacu-Tite!
Dorman 494-103 Package number 47403
Advance Auto Parts SKU 5707153 $2.49
On the subject of the Hallman ES Controller, is this a Bleed hole here? If so, won't it send false readings to the stock wastegate solenoid, as well as slowing the reaction time?
Next point to ponder... If the Wastegate solenoid has 1/8" tubing feeding it, won't 1/4" hose give too much volume for accurate/fast reaction time to boost level changes. How about this setup?:
2003 Onyx Green PT-GT
K&N Drop-In Air Filter
Kenwood Sirius Satellite Radio System
Garmin Street Pilot III Color GPS