Let me be the first (and probably not the last) to say stay away from delta mic, pay the extra and get a better make, thats from experience
Exactly why? I ran them on an abused track car, a low ph1 an now on my current ph1 with them too. Not a problem, EVER!
I had them on mine and it ended up as:
Quite a few other stories in: http://www.cliosport.net/forum/show...ng-sound!&highlight=fixed+that+knocking+sound