Will mods void my warranty?

Modifications do not act like a global switch that voids everything. What they do is give the manufacturer grounds to decline a claim they can connect to the modification - and that connection is where the whole question actually lives. **The risk is not evenly spread.** It concentrates almost entirely on powertrain, which is also where repairs are most expensive. An unrelated claim on infotainment, trim, suspension or electronics is far less likely to be affected by a tune. **Low risk, in practice:** cat-back and axle-back exhausts, wheels, tires, shifter parts, suspension, brakes, cosmetics. None of these change fueling, boost, torque or airflow, and they are generally viewed as unproblematic. **Where resistance should be expected:** anything that changes what the engine does. Tunes, intakes, J-pipes, flex fuel systems, upgraded turbos and fuel system work. **The detail most owners underestimate:** returning to stock removes the map, not the history. Modern Subaru ECUs retain a record that reprogramming occurred, and a dealer with the right tools can see it regardless of what is currently loaded. Flashing back before a service visit is damage limitation - it means a technician sees a factory map rather than an aggressive tune, which is a meaningfully better position - but it is not the same as the car never having been modified. That is worth knowing because a lot of advice treats flashing back as though it makes the question disappear. It does not. **Dealer variability is real** and the community reports it constantly. Some dealers are mod-friendly, some are not, and which one you have matters enormously. Building a relationship with a service department before you need something from them is genuinely worth doing. **Practical steps that improve your position:** Save your factory file before your first flash, so returning to stock is always available. Keep every factory part you remove, because a stock map on a car with an obvious aftermarket J-pipe is not a convincing combination. Keep maintenance records, because a well-documented car is a stronger position in any dispute. And be honest with yourself about the tier - a Stage 1 map flashed back before service is a modest, manageable risk, while a flex fuel system or a J-pipe is physical hardware you cannot flash away. The safe working assumption in the community is that once you tune, you should expect much less powertrain protection. That is not a reason to avoid tuning. It is a reason to decide deliberately, while you still have the coverage, rather than discovering the tradeoff after a failure.