The Cusco mounts all use some type of rubber bushing around a bolt. They don't appear to be anything too crazy, from what I can tell. Definitely a far cry from a solid billet mount. From the looks of it, I would guess they're less stiff than the polyurethane bushing in the Kartboy mount.
But I guess from what I've read online, the Cusco's are very, very stiff, so maybe I don't know what I'm getting into. I'll install them all at the same time. But I can swap back to stock if I want to experiment. The motor mounts are the only ones that are time consuming to install. The pitch stop is literally 5 minutes and the tranny one is probably only 10 minutes after the car is on stands.