I just upgraded to Flashscan Personal from EFILive Pro. After doing some reading on this forum I now more clearly see the advantages of spending the extra $150 for the Commercial version. In the mean time can I still modify my current GM factory OS which is a 2004 with the Personal version? I also have a 99 Silverado and am wondering if I can upgrade the 99 factory GM OS to more current GM OS with the Personal version or if I need the Commercial version to do this update. I have modified both of these motors with StageII heads, Comp camshafts, 1.85 Pro Mag rollers and long tubes. They are strickly N/A and I plan to keep them that way at least for the near future so I'd like to get an OS the is N/A compatable.