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This does not really make sense. You need to be more specific about what "YOUR" bank limit is and what you really want to achieve.
If it is just HP as you posted buy a Nitrous system. LOL
And or get a Versa Tunny kit/program VersaTuner
You also should depend on your miles and few other items do a complete health check of your engine.
Then before you started adding power supporting or building parts and systems get a base line DYNO run.
Don't be surprised if it is not what Mazda specification are printed. ( I carefully choose that descriptive word)