ARMS made this revision to the IT rules as a total common sense rule change only. The metal headlight cover has to be of the same profile as the existing headlight (take a look at the photo). This rule has worked for us for years without any issues, ie: no performance gains, really. This actually "lowers" the cost for IT racers by allowing them not to have to buy expensive headlight replacements as well as no glass on the track in the event of an incident. It just makes good sense.