Wow, obviously lot's of educated engineers on this forum. Cool
I just stayed at a Holiday Inn myself. Heck, I've heard of many instances of spring hanger failure on these rig,s without any additional stress. Personally I wouldn't risk additional stress on an oem application with something it wasn't designed for without shoring it up. I'm not referring to the new cross members as those do nothing to help the actual oem hanger connections to the frame. Maybe if the fabricator had replaced the oem hangers with the stout hangers he added to the new sub-frame that would have made me more comfortable.
Again, just my uneducated observations. YMMV
