Welcome along!
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A stage 1 map will require nothing to be done to your car beforehand. Really all you'll need to check is the usual precautionary items. Make sure your Diverter Valve is a nice new Recision G one, check your PCV is ok, Coilpacks are the latter recalled ones and run it on 99RON.
What car do you have? If you have a standard GTI then expect to see around 50 bhp and 80 ft lb torque from a generic map and similar gains from a K04 Turbo'd Edition30/Pirelli. As for a map, go for the best and not the nearest IMO. As a R-Tech fanboy I'm going to say them but you can't argue with REVO or APR.
Happy modding!
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