Unfortunately, many places you would go will associate the mods with aggressive driving habits.
Aggressive driving habits is referred to as abuse of the car.
Abuse of the car is immediately voiding a warranty, as abnormal wear caused by the owner/driver.
Installation of non-Subaru OE approved parts, is another way of a warranty voiding.
Of course, some will carefully word things, to coincide with the Magnuson-Moss Warranty Act.
In other words, to have the original powertrain warranty and/or the bumper to bumper warranty to cover you, well you may be SOL.