Bruce_Willis

I have a Greddy exhaust on my Accord which is pretty loud but today my friend was in the back seat and said he heard an intermittent buzzing that I could not hear from the front. Tonight I'm driving and now I hear a constant hum which sounds like it's exhaust related.

My friend said it maybe heat sheild?

Any thoughts

KMFDM

its hard to say but a humming coming from the back could possibly not be related to your exhaust but could be one of the rear wheel bearings

BONE

well I remember when I installed my WS on my Integra it used to make a different noise while I was driving the pitch used to change but as the exhaust broke in the noise went away, give it time see what happens.