According to Skunk2's website, you will need to upgrade your valvetrain to support this modification. I'm assuming they mean valves, valve springs, and retainers to complement this upgrade.
They are not CARB legal. The Stage 1 are CARB-EO pending, again, according to their website.
So if you are in cali then you may run the risk of not passing.
Quote: Stage II: Stage II profiles are more aggressive than Stage I profiles, and are designed for modified engines operating at higher rev ranges. Upgrading to Skunk2 Racing valvetrain components is required for proper operation. Stock idle and emission characteristics may be slightly compromised, but fair-to-good driveability allows them to still be used on dual-purpose vehicles. Proper tuning, an upgraded intake system, and an exhaust system are required in order to maximize the potential of these camshafts. Do not use oversized valves.