I think I have either bad motor mounts or a bad trans mount. When I accelerate hard I hear a loud bang on the trans tunnel in the car. Is that my trans mount or engine mounts? I am going to replace both no matter what but I just wanted to make sure its either one of those and not anything else.

Sounds just like someone hits underneath the shifter with a hammer. (A4 with a shift kit)

 

Oh also forgot to mention this. When I turn like coming out of a parking lot, the car feels like its swinging around on the rear end. Hard to explain, almost like it's fishtailing but no tires are spinning. I'm afraid the whole underside of the cars just going to come off. Funny thing is when it's up on a scissor lift nothing looks or feels loose. Any Ideas guys?

 

also look at the torque arm make sure the front bracket on it is still clamped together. mine made a horrible bang when accelerating and i didnt notice it upon first inspection, try that too.

 

Sounds like your trans mount. I had the same thing happen just a couple weeks ago. The mount is rubber and the rubber actually split apart. Try lifting up your trans a little bit by the driveshaft, if it moves then the mount is ripped apart.