I swapped out my rotors a few months ago and just changed my pads to Posi-Quiet because I was wanting a good DD brake pad. They seem to be fine for the first couple of stops but after that they squeal horribly, mostly below 30mph. They're semi-metallic street pads, so bed-in shouldn't be necessary. However, I tried it anyway (7 - 60 to 20 hard stops)...
I greased the back of the pads when I put them on and they all have metal shims that they came with. Not sure what else to do at this point and it is driving me crazy!

 

from another thread of "Bad squeaking breaks so i need recommended aftermarket brake pads" evoxisking said "any pads that are non metallic = no squeaking". hope that helps

 

That's strange because I've heard the opposite, that ceramic pads will squeal so that's why I went with the semi-metallic. Certainly expected Posi QUIET to be quiet.

 

I have ceramic pads and hate them. They don't stop as good as OEM and they squeal the first couple of stops after a rain as if they have rust on them that needs to be worn off...weird since they're ceramic.

 

Yea I traded that issue for the issue i have now, which seems to be that when they're warmed up they will squeal (unless applying the brake with a lot of force).

 

ceramics are not really good for hard braking more for daily driving. The material is good for daily cause it has longer lasting wear characteristics. The Semi Metallic brakes are good for our cars due to the high heat resistance yes they do make noise but they are less submissive to brake fade. They squeak from the brake dust and cracking sometimes.