Neither the exhaust nor remap will void the manufacturer’s warranty, however if a fault occurs which is attributable to the modification - or even could have been caused by the modification - then your manufacturer’s warranty won’t pick up the cost of repair. Tuners sometimes offer insurance (often described by the tuners as a warranty) to cover this eventuality.
Generally plug in devices are more compromised than a remap. Many tuners offer both tuning devices and remaps, even Brabus, but plug in devices provide the smallest performance improvements of the two options. Ultimately it comes down to which is the bigger compromise, reduced performance or having to reapply the map if the dealer ever overwrites it?
What’s the reason you plan to “switch back to stock”? If it’s so the dealer and manufacturer don’t know you’ve tuned the car which could potentially prevent a warranty claim, then if the warranty claim is big enough, and they want to, then they can look for the tell tail signs left behind even after a a tuning device or remap has been removed.
It’s not really fair to expect the manufacturer to pick up the bill for the owner knowingly increasing the risk of a fault occurring by increasing the power beyond standard, and in some cases using an inexperienced or bullish tuning firm. Instead it’s best that owners underwrite their own risk or insure against it, and get the safest possible tune from an established and experienced tuner.
it’s a bit like buying a suit, then choosing to take it somewhere else to get the legs and sleeves shortened. If the person doing it goes a bit too far, and takes off a bit too much material, then it wouldn’t really be fair to expect the person who sold you the suit to pick up the bill for sorting it out. The owner of the suit took the risk, and so they should accept the consequence if it goes wrong.
