I was told by my dealer (who had asked the factory) that any Stage 1 (or higher) kit other than the factory supplied one (which you can’t get at the moment) would affect the warranty (which is why I have not fitted a G56 or KH one and am waiting for the factory ones to become available again). As to whether MMC are within their rights not to honour the warranty in these circumstances is a different matter. Given how often my car has gone wrong and been fixed under warranty, I didn’t want to put myself in the position where I might have to have an argument with the factory about whether the warranty did apply or not.
