auraaura

Ever since I put headers on my ride I have a slight resonance at about 1900 RPM. Not a biggie. Until recently. My parking brake has starting buzzing like crazy at that resonance point. Unfortunately that's around where I have to cruise to avoid speeding tickets. It's driving me crazy, it sounds like a supercharged bumble bee is loose in the console. Has anyone else experienced this, or better yet does anybody know how to fix it? I can hold the brake lever and it will stop but that gets kind of inconvenient.