Between remapping to “Stage 1” and a tuning box, the difference in power is small if there is any difference at all.
Stage 1 remapping will usually involve increasing the boost pressure slightly which is exactly what a tuning box does.
The differences between remapping and tuning boxes occur when you start changing parts on the engine, for example you fit a high flow downpipe with a race catalytic converter or if you radically change the intake system for example changing pipe diameters.Fundamentally a tuning box exploits the parameters built into the factory ECU from the factory. These parameters are largely based on the volumetric efficiency of the engine and this is especially true for turbo petrol engines from 2010/2013 onwards.When the volumetric efficiency is changed the sensors on the engine will start bumping into the limits of the factory software for example air flow measurements and boost measurements.Some cars will be able to operate with quite large changes to the parts on the engine ie race cats and high flow downpipes, other cars will have engine maps which are more strict.The compatibility of a tuning box with engine modifications is down to the factory software and the factory software is going to dictate the limits of the tuning box.Remapping and engine however gives you total freedom with regards to how much boost you can run.The benefits of this is that you are able to radically change the volumetric efficiency of the engine but the downside is that the limit you will find will be mechanical.ie remapping an engine opens up the possibility of melting pistons, putting a rod through the block, putting holes in pistons etc etc etc.With a tuning box the limit you will bump into will be electronic. Because the tuning box does not change the factory safety parameters ie air flow, air fuel ratios, ignition timing you will get a check engine light before you get engine damage. (Assuming the engine is in good condition, has been serviced properly and the factory software does not have bugs which allows the engine to work outside safe limits)
Remapping an ECU gives more potential for power but also makes it possible for the engine to be mechanically damaged if the tune is not good.A tuning box is designed to work with standard, unmodified engines which limits to amount of power it can make but the limits it runs into will be electronic and not mechanical.If you want to keep the factory software unchanged because the car in under warranty or because the car is leased then a tuning box is probably the ideal choice.If you want to change the exhaust system, your car is out of warranty, you want to fit a bigger turbo and bigger cams, the a custom remap or a programmable piggyback ECU is the only choice. A tuning box is simply not capable of adapting to these type of changes.You can purchase tuning boxes and programmable piggyback ECUs from Street & CircuitClick here for tuning boxesClick here for programmable piggyback ECUs