I notice they say "429 lift / 256 duration. Recommended for all 1996-later 2.0L 8V engines. This is the most aggressive lift and duration you can run on an OBD II engine without triggering an engine check light."
For a start the mk3 has no engine check light, and it's a lie about that being the most aggressive cam because I ran a 285 with 11.53mm lift (.429 is 10.89mm) and it caused no problems with the lifters or the head.
http://www.kentcams.com/Go there, and search for gs23h

gs22h is a bit milder, 260 duration but 11.17mm lift. Looks like kent like making cams that sacrifice duration for lift.
You could change the lifters if you wanted to, and to be fair it'd be a wise move as any lifters that may be on their last legs will pack up due to the extra effort they have to make. You can get a new set of 8 from ebay for £30 odd. Make sure you bed them in which is something I missed out, but it didn't cause any problems.