Take a look at my posts #28 and #29 in the link below. The runs were all measured using a dragy, on the exact same road.
should be able to tell the motor power because the voltage and current are all measured and reportable. i test drove a YLR vs my 3P and the biggest difference is the immediacy of accelerator response. it *feels* as if they smoothened out the torque vs pedal mapping curve. the 3P is ready to...
teslamotorsclub.com
The acceleration decreased as speed increases. But at the top end, it still is slightly faster than stock. Your butt dyno probably might not notice the difference up top but it does exist.
The 980 motor is needed only for using the ghost module from Ingenext and whatever equivalent teslogic has. That's because the old performance cars (not sure if the new ones have the same old motor too; I'll check my new MYP and see) came with the 980 motor. Some LRs also came with it and basically all it needed was a software to make the car think it was a P and not LR. The newer ones (including my MYLR) come with a 990 motor. It's not what the P uses. Thus, these cars cannot be "tricked". What the Ingenext/teslogic software does is trick the car into thinking it has AB. That is why 0-60 is same as an MYLR with AB. Of course it also has additional features that you won't get with AB. Reason I went with AB was because it is offered by Tesla and there won't be any warranty issues.
Regarding new cars not having AB. It doesn't depend on the motor. It's more likely it's a battery issue. I know a lot of people with the new 990 motor (me included) who have AB and no issues whatsoever.