Most newer brake systems have "groan" issues. Long story short, you used to ahve smaller, hotter brakes with semi-metalic linings - i.e. steel wool that did a nice job of keeping your rotors clean. They did not stop as well, lasted maybe 30k miles, squealed when hot, but they did not "groan".
Now you have "NAO" - Non-Asbestos Organic linings that last much longer, your brakes are bigger and cooler and better but the new linings leave lining material on your rotors.
I put Performance Friction linings on all my vehicles when I change the linings. They squeal when hot but they keep the rotors clean and stop great.