I believe Tony was hinting that if and when you sell the car, you should note that a turbo back exhaust was equipped on the car for xx,xxx km and no retune of the ECU was done.

Running a turbo back changes the way in which the engine behaves, but the ECU can't know this until a retune has been done.
Having a retune can potentially save your engine from going dak dak dok.

N.B. the above is my opinion and should you be worried about what was written, please contact one of the tuners in the Perth Workshop thread to seek advice from.

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2015 Forester XT Premium
2020 VW Tiguan Allspace
teejay: If I wanted a comeback Id wank in front of a fan