Okay, so a while back I got some EBC slotted and dimpled rotors installed, along with some unknown brake pad from the shop (cause autoanything sent me the wrong EBC pads). I was never fully satisfied with my brakes afterward, too much noise (Even when I wasn't braking), longer braking distances...

Fast forward to a couple weeks ago. Took off the shop's pads, replaced them with Duralast C-Max ceramic pads... Bled the brake system in circuit order in case some air got in the system. Did it a few times, maintained fluid levels, pretty much cleaned out the old stuff.
Brake noise disappeared.
Brake pressure was the same, I thought.
And there is more pedal travel.

Now under heavy braking, it seems like they grab only so much (not much at all), no matter how hard I press on the pedal. Got so bad that I had to pull off the road and nearly hit a post going only 30 mph cause the car wasn't stopping.
Also there was a deep/whirring noise while braking... totally ruined my day.

Any similar incidents? Problem solvers?

 

how are your calipers them selves? does the piston move somewhat easily when pressed in? did you grease the slider pins? are the rotors warped?

 

Sounds like there could either be: air in the system still, the master cylinder is starting to go bad or the rear brakes aren't working correctly. That is all providing the front brakes and calipers are working correctly.