General Maintenance & Repairs - Double bump when 4L60-E shifts

I have a built 4L60-E with a 3000 stall and when the car shifts from 1 to 2 you feel a double bump in about 1 second of time and my custom dual exhause hits the bottom of the car, I don't know if the car is squating a little when this happens but you feel movement in the car from the shift and you really only feel it when you get on it some (half pedal will do it)...it's real annoying and I don't like my exhaust hitting, does anyone know what is happening and how to stop this?

I have on my car:
Koni fronts
Bilstein rears
boxed rear support arms
welded sub-frame connectors
after market (but still rubber) tranny mount
poly engine mounts

Had the same thing happen to me twice in an '95 LT1 4L60-E, turned out to be a broken tranny mount on both counts. Stay out of the throttle till you get it fixed or get ready for another transmission rebuild.

Just changed mounts to a 1le mount so I don't think the mount is broken, maybe the tranny/engine is jumping and that's what it is but with the poly engine mounts the engine should not move much, maybe tranny is still jumping even though and maybe the 1le tranny mount is not strong enough?

I would pull the tranny mount again and check, I broke one and the the other less than 1 week after. Very possible to be sold a crappy mount.