Yep, the 450's and 700's now have been around for a number of years and the builders have figured out how to get some pretty awesome power out of these quads.  Problem with this is the 450's are high strung from the factory to compete in motocross races.  The builders have punched these out to near 600cc with the supporting mods.... but that is all at a H U G E cost.  But speed costs.

I love pulling up to Olds or China wall and running my built Zilla up and down for a few passes then park.  Many people come by and are impressed that this 20+ year old technology is 1) still running and 2) runs as well as it does.