Injectors don't 'push' fuel. They are electrically controlled, ultimately crank sensor timed, solenoid operated , calibrated valves. Operating perfectly, which is not always the case, they either prevent or permit, during an induction stroke, a monitored fuel amount to enter the cylinder they feed.
Learning is fine and here's some advice...Sixteen year olds being able to drive WRX on the public roads and worse 'modified' ones should not be permitted...in other words on presentation of your licence for the registration it should be denied. More concerning again is that you bought a tacked-together nondescript motor to 'hot it up' and now want to 'hot it up' even more, having already a half baked job done now without expert redoing of brakes and steering. Personally I am 'tired' of hearing mania about Cobb and other so called 'tuners' perhaps fantasised-about or worse again, employed as a rite of passage to get accolades here. What I'd like to hear more about is responsible behaviour and commonsense. Your car will not have insurance payout if examined after an accident and requires an automotive engineering certificaton by an appropriately licensed engineer to be properly registered. That means, if the Insurers are vigilent, that you will be paying out for damage to property or 3rd party victims whether you are at fault or not. If the matter becomes a civil claim your car will be examined and reported upon and there will be no escape from liability.
Registering it under the old details and not revealing the mods would see you again vulnerable, in this case to a 'plates-off' on the spot deregistration by police. The wisest course for you is maintain your motor standard...exactly standard ...register it under the new engine number...keep it standard and learn to drive with 100% awareness and consideration of those around you. That will not happen with a rev-head mentality or dreams of tacked-together after market bits and pieces 'tuned' by 'experts'. Unfortunately what they do in power-boosting client cars is not compulsorily reported to the Departments of Motor Transport and requiring engineering examination and mod's recording and sent to insurers before the car can be taken from the 'tuners'. I'd go further and say every car who's owner wants modified should require a certificate from Motor Transport allowing such modifications and no more and then engineering inspection within a week of the car being released to the client. "tuners who exceed the permit would face shut down and prosecution.
Subaru know how to make their cars, without the level of 'expertise' presumed by people who write about what they are going to do 'oy oy oy'...to their Subaru or who sell aftermarket bits and pieces. As well as producing a saleable car Subaru has to meet braking steering, reliability, materials suitability, quality assurance and quality control, "pollution" and any other state or national demands and standards. They have to be prepared and enormously insured against design or installation 'gone wrong'. They have access to the finest materials, laboratory precision and designers. They have to test each model under onorous conditions...test and fix test again and so on.. Their car has to then stand the rigors or some lead-foot revheads.
Subaru could deliver their cars with 300kW motors but they do that only with properly designed, engineered ,built and tested cars put together as an 'entity'...a 'package' .... a 'formula' a properly thought-through array of parts and philosophies costing money you could not dream of owning before they get approval to be sold and in various strictness in various places. ...for example the STI.
This is my advice after decades of automotive experience. Stay standard, stay safe or realise that you are a public menace in safety and insurance with the modified vehicle or the way you drive. You will suffer the real consequences if things go 'wrong'. It will not go away. Garnishing your wages and selling your assets which may include your car or what remains of it are some of the consequences you and others may face. What you do now to your car might affect years of your life and the ability to move ahead in more important areas of life.