Not going to get into whether this particular mod is desirable or not, that's up to each owner. But on the notion of a manufacturer "voiding" a warrantee because of a "minor" modification, that can't happen as it is prohibited by Federal Law. As a simple example, Toyota cannot fail to honor any part of the vehicle warrantee (e.g. engine failure) they offer if you were to install a set of custom wheels for instance. Now, if you make a claim for failed wheel bearings within the terms of the warrantee, that portion of the warrantee may end up in dispute since it could be related to the owner modifications.