[DeTomaso] Valve cover sound, strangest question of the day?

[Mikael]

This may seem like a strange question, but has anyone experienced a change
in the mechanical sound of an engine by switching valve covers? I replaced
the Ford Racing chrome covers this winter with fabricated alu valve covers.
Man, they look good. But at idle, now I hear more valve train noise than
exhaust noise. Can this be? I can of course have a valve train issue, but I
don't think so.

Mvh/Regards
Mikael