Asked over on the avid site as well. I have an avid flyer and I put vortex generators on. My ops limits state that any major change I need to notify the cognizant FAA office and get their response in writing prior to flight. Well I contacted the FAA and have been less than reasurred. I have gotten anywhere from "its experimental so do what you want just be careful" or call such and such and he would never answer his phone. I called a DAR that was recomended by an faa guy and he said any inspector could help me. Well the inspector I called today in his 3 yrs with the faa he had never heard of something like this. He did say he would find out, but after saying I would have to have it evaluated and all kinds of math to figure out the possible effects on flight all while saying he has no idea who to have that done. So any ideas on what I need to tell the FAA? I am trying to get legal prior to my condition inspection. Or am I being overly concerned by this? I would suspect a a+p would see vgs and go hmm if there is no mention in log books, but I have never had a plane inspected. Thanks Mark Whiddon