Ron Adee was one of the first people to get it done (by Autoform). At that time (many years ago), Autoform was installing the center vent and painting (just the vent) for $1,500. I asked Ron about it after he had it a year, and he was very happy with the quality and durability. I ended up getting a replacement hood from Autoform with the three vents across the top, instead. I now have two of the Autoform hoods. I have wanted to get the center vent installed on my ACR hood, but for some reason I am still gun shy about having a hole cut into a perfect hood. Autoform uses a template to cut the hood so the vent sits recessed/flush w/o damaging the surrounding factory paint. As mentioned, they just paint the vent. In the standard GTS-R location, the vent releases heat from behind the radiator. It opens the hood from the airbox to the throttle bodies.
Paolo had his vent installed further back on the hood by Alcalde (sp?). You cannot see the seams, and they repainted the entire hood.