I had a hybrid 2.5 with 2 liter heads installed in my 2002 wrx.
I had it done by CAN -JAM [ Canadian Rally team] they also
installed a bigger turbo[ i supplied] an a inter cooler [i supplied]
The car already had a 3 inch exhaust an polished intake and
throttle body- bigger injectors - bigger fuel pump $9200. +tune
It is not a wam bam job. To get a proper tune the car was put
on an all wheel dyno. What seems like negative comments are some time
hard to take but most are designed to help.
Live Long and Prosper