Specifically performance mods? I have a friend who has a '60 something bug with a 2100 cc motor and dual webbers. It runs, but poorly and way rich, and won't pass emissions. He had it a shop a few years ago and they told him that it just needed a good set of performance heads and it would run like a stripe @$$d ape. He is pretty non technical and asked me for help in tuning it up. We are planning on pulling the motor and putting new seals/gaskets throughout and replacing the heads. Anybody have any idea where to start on selecting heads/cams for it?