Been a resident of the ACS hometown for nearly 10 years
But I have yet to see a proof that ACS mods don't invalidate the OEM warranty! That is just not true, at least not generally speaking. Here the official statement from their website, read between the lines:
"For your Information:
Conversion using AC Schnitzer components does not affect the fundamental warranty obligation of BMW AG in relation to the complete vehicle. The BMW warranty can only be excluded in the special case of a claim which is directly attributable to a conversion. BMW vehicles upgraded with AC Schnitzer components are therefore not automatically excluded from the warranty. We would be pleased to supply corresponding information on request. "