detaching the the battery cables will not do anything. if you get different injectors you will need to have the car programmed by a tuner no way around it. by changing the injectors you will go outside the factory parameters.
ECM CANNOT compensate enough for mods you do to either int or exh Theres set parameters that your ecm can work within tunes change these parameters. Without a tune If any there will be slightest bit of gain til it's out of range of the ecm and will not be noticeable. Theres a chance that your "bolt ons" can lose you power.
Every person that comes to here stop asking the same question that is answered with this same answer. It's not going to be any different when you ask.
this also applies to fueling modifications.