well technically anything that modifes your power level of your car changes the emmisions on your vehicle, but u just put it in and put it in a spot that is sort of away from view in cabin then u will be right, also with that missfire and flat spots in rev range, all u have to di is regap your spark plugs to 0.8mm and it shoudl eliminate your problems on missfiring on standard ecu when it richens up bcoz u are running more boosta nd fmic. simple fix.
yet again not sure about legalities of aftermarket ecu's but with power fc it slots onto standard pspot and look stocko, just dont have your controller plugged in and on your dash incase u get pulled up.hid it in cabin.