The tranny is electronic but still relys on fluid pressure to tell the trans ECU what to do. The trans is nothing more than a big pump. Try not to lift off the throttle right before it would normally shift, this causes the pressure that was building to cease and the ECU sees that the vehicles rolling speed is now deservant of 2nd gear rather than a higher RPM 1st gear. If you must accel only to roll slowly try to accel past the first shift, then decelerate. This should help you clunk/thump. Hope this helps and makes sense.