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Yes, if you're going to approach it from a "what's the maximum return I can get for my money?" point of view, then a remap. BUT... Your car will feel much more better balanced to drive if you enhance the suspension and brakes as well or even first.
With more power you'll find yourself wanting better braking power and handling and such mods as anti-roll bars and Quaife diff can transform the car further. You'll want to be able to transfer that power to the road without wheelspin and so a lower engine mount will help. The slippery slope is expensive as it all adds up.