2500 rpm grinding feeling/sound
 

Right at 2500 rpms my car makes a grinding sound with or without the car being in gear. Not sure what it is, I did a new fuel pump w/ rewire and put on a differential brace before this problem came up.... any ideas?

Sounds to me like something vibrating at a natural frequency that matches that RPM. Check all your heat shields, etc., to see if one is contacting something it shouldn't, especially in the area where you did recent work.

Sounds like your diff brace has caused something else to start vibrating. Give your car a good look on the underside to see if anything is loose, or touching something (when it shouldn't be).

Where is the noise coming from?

Sounds like its underneath me and in the engine bay at the same time. At first i thought it had to do with the driveline since i stiffened up the diff. But like i said it does the same thing in gear or not.