Rep Power: 0

So my wife's 2009 civic ex has an extremely loud hum ( almost like an after market exhaust) and a vibration that shakes the ENTIRE car, especially when first started. New motor mounts just put in. Idle is a little back and forth too, not to steady. Could it be the exhaust manifold?

 
Rep Power: 243

Yes I would check all your exhaust connections from the manifold back.

 
Rep Power: 0

I appreciate it. I really inspected all 3 engine mounts and realized they are worn down and need to be replaced. I'm going to start there. As far as the mount I thought it was replaced but come to find out it was just the dog arm.

 
Rep Power: 222

Cheap engine mounts will give you more vibrations