Cold air intake do not cause valve damage. I have read several article and none of them metion valve damage. But CAI may cause hydro-lock cause engine damage. CAI use cold air molecules which are less dense. Being that they are less dense their structure can break down quicker and cover more surfuce area of the piston. CAI mainly have a power peak 5K rpm range. But being that CAI are longer they tend to bring air in slower. Your engine tends to not like working for its air. So as you can see CAI has advantages and dis-advantage. Short ram bring air in quicker, but because the air is warm being that the short ram is inside engine bay it air is very hot. For more info on air intake check out some article on team-integra website.