17.7. ANTI-SWAY BARS
A. Any anti-sway bar is permitted. Bushing material, method of attachment, and locating points are unrestricted. This does not authorize removal of a welded-on part of a subframe to accommodate the installation. Components such as anti-roll bars and strut housings which serve dual purposes by also functioning as suspension locators may not be modified in ways which change the suspension geometry or steering geometry.
Here's my take -- you can't remove any of the stock subframe, but you can you make it beefier. Legally.
