You can knock the baffles out on an EFI but you will still have the cats in the front of silencers which will still reduce the flow. The result will be louder but not improved performance. Consequently you would not need to remap.

Cheers, Richard
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09 America, Staintune Pipes, K&N, Breathe, Hagon Nitros, AI & O2 removed, tune 20184 (modified), MTX-L a/f gauge