as i have been reading i keep coming across people say that the 02 and 03 wrx ecm computer has more learning flexibility than newer cars. i already know that i need to tune and am gearing up for ecm college thanks to unibomber and a few others that have recomended reading before tackling opensource tuning or romraider...whichever. havent got that far yet, school before tools. my question for fellows already graduated is can i diy port n polish my factory exaust manifolds and crossover pipe safely already running a grimmspeed up pipe and new timc hoses? i understand that the motor really isnt producing more exaust if i do, but i am worried about spooling the turbo to quick for the computer to push fuel(read...need tune)making lean=bad on high mileage motor. if it can learn the extra flow, great 'cause im dropping the manifolds anyway for new gaskets and a left side bore n tap for egt sensor. otherwise it will be a in and out for the sensor and new gaskets. then, read read read lol, tune.