what upgrades have been done to 3vz's?can a supercharger be put on

There is no supercharger for specifically the 3vze. You'd have to custom fabricate the stuff if you wanted to. Also, with any kind of boost, you'd need to upgrade the internals and gaskets.

Bluefever---go for a new engine, its best if your looking for power. There is a lot of stuff you can do to the V-6 but it takes money, port and polish, headers, oversized pistons etc....

try a nitrous kit...