A custom tune will get you better performance and safety, assuming a good tuner. AP or OS, doesn't matter. Might as well stick with the AP since you already have it...or sell it and buy the $100+ cable you'll need for OS data logging/map switching, etc. But you'll lose the convenience of the AP...which may not matter to you.
If I needed a retune, I'd call Ed at EQ Tuning in Fairfield, CA every time. My car has been amazing with his tunes.
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Slow and low, that is the tempo.
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