On the passenger side suspension tower, you will have a stock boost controller solenoid.
this will have hoses comming in and out of it.
one goes to the wastegate actuator and the other goes to the intercooler piping.
when stock, one of those pipes also has a tiny little restrictor in it to make the boost stay at 7psi.
so..
when you got a fmic installed, if they didn't connect the hose to the wastegate actuator or to the NEW intercooler pipe, you will have no boost control, therefore the wastegate will stay shut causing all the exhaust gases to go through the turbine wheel, making massive amounts of boost.
If it is all connected, they may have changed the hose or hoses from boost controller to new ones to fit the new piping and therefore the restrictor is gone and now you will have about 14-15psi if I remember correctly on my old S14..
so in a way, a new boost controller will solve your problem..