I realize that you can get away with using standard headers, and most of us have no issues doing so on our own cars, even if it means a little extra work to change plugs, or using 90* boots, or cutting down plug sockets, etc.(I'm using Flowtech LT's on mine) I suggested P specific, only because he is installing the engine in a customers car. If I took my 'stang in to a pro to have a new engine installed, I would want EVERYTHING done right, even if it meant a few extra $$$$.