Someone used to make a supercharger kit for these a long time ago. I saw 2 supercharged GLs in person in the mid 90's, both identical and were bolt on kits that were purchased. Not sure where they came from but they used a downdraft automotive carburetor (2 or 4 barrel can't remember) that sat on the supercharger with it's filter inside the false tank as GL tanks are under the seat. I like the way they retained the look if the individual runners going into the ports. The kits I saw used an ugly one piece cast manifold that sat low in the middle, looked like two wedges of cheese coming out from under the supercharger. Nice to see someone doing this again!