To clarify this...
Put wheels on the car that use hub centering rings*, have a slightly different offset** & weight*** (66.1 v 56.1*, 38 mm v 55 mm stock** & weigh about 6 lbs less***).
Service rep mentions wheels are not OE spec & that may void warranty on adjacent mechanicals (shafts, calipers, suspension parts etc... ).
To this one replies... "Unless you can support an assertion that the wheels actually caused an issue... no".
Am definitely not pushing the idea that one can mod to their heart's delight and be protected by Magnuson-Moss.
Along those lines I would not modify suspension components, catalyst, federally mandated emissions equipment or an ECU (etc...)
With local labor rates currently at $130 an hour, and parts costs rising every day, I'm one who needs my warranty intact.