Grand Am performance

I have recently been looking into speed parts for my 96 Gt, And rsm racing seems to have some stuff , Ported Heads, intake manifolds, throttle body's.......... but im wondering about Fuel injectors if i replace the stock heads intake manifolds and throttle body aswell as exhaust , would the injectors be able to be "tuned" or would i have to scrap em.

Another thing is , their seems to be no exhaust headers for the 3.1L i know that the 3.4L is a different block, but would a 3.4 exhaust header work on the 3.1?

And one other thing , sorry for the long assed post,

Can the stock trans hold more power? can the 4T60e hold over 200? Im guessing but i think ported heads intake manifolds throttle body exhaust headers into 2.5 exhaust with high flow cat would give me more than 200hp . If the 4T60e cant hold it , can it be rebuilt or would it be cheaper to go with the 4T65E trans and rebuild that?

And im not sure about the ECM , do i have to buy a ecm tuner to make changes for the increased airflow?

Thanks,