Hope that's the case - i.e., it's not rod or crank noise. Valves are adjusted via shim over bucket so valve noise is fairly uncommon though - unless lash is way, way out of spec - out as in it has spit a shim out and it's clattering around on top of the head...
A loose nut on the EGR pipe (at bottom of the EGR mount) is a fairly common occurrence with the 6VE1 however - and it sounds a lot like valve clatter - almost as bad as a diesel - but the fix is quick and simple and CHEAP - so check for tightness before you start trying to chase down noise in the valvetrain. If it needs tightening, a 22mm stubby wrench or flex wrench will make life easier.
If it's not the EGR then check your timing belt tensioner ASAP, as they have been known to fail and cause valve train noise. This is very important! You do not want your VX to jump time as it's a PITA to get it happy again and furthermore some say we have an interference engine so it might cost more than just your time. You're coming up on 100K miles so it's time for a new belt and tensioner anyway...