Exhaust Vibration after H-pipe install

I had the 97GT all apart to fix a broken shift fork. It was bone stock, but I decided to install a BBK offroad H-pipe while everything was apart.

The BBK pipe had hangers to use the factory rubber midpipe hanger, and I used these. To make the pipe reach them, I had to jack it up, so there was quite a bit of tension in the rubber hanger when I let them down.

Now, I get a good deal of engine vibration at lower rpms through the car. Anyone had this happen? I suspect it is related to these rubber hangers being streched a bit too far, and transfering the vibration through this mount. Anyone able to say yes, possible or nope?

yeah, I can understand, but it's definately not the rumble.

Idle still feels pretty smooth. But if I let the clutch out from idle without touching the gas, it vibrates quite badly inside the car. I used to do this all the time and it was smooth.