[verrilli]

I used the value in the ducati manual, 2.3 degrees.
Once I set the throttle plate fully closed and reset with the VDSTS, it displayed 3.2. I don't know why this is. I asked LT and also tried to ask the VDSTS folks but did not get a good answer. So I just used the VDSTS to adjust the throttle so that the difference from the dead closed setting was 2.3 degrees (to 5.5 degrees in my case) and then reset with the VDSTS again. So at the end it read 3.2 degrees.
I don't think it's necessary to set the base to 150mV on the ST3. That's what the VDSTS reset is for. The ECU just uses relative voltage difference.

 

[verrilli]

Please note that the ST3 ECU is different from earlier ST2 and ST4. The ST3 ECU has the ability to program the reference value which is the voltage at 2.3 degrees. This is what happens when you do the VDSTS reset.
If you think about it, the ECU doesn't care what the voltage is when the throttle screw is backed off all the way. It never gets there during normal running. All it cares about is what is the voltage at 2.3 degrees. From there it can use the relative voltage to figure out how wide the throttle is open.
The older ECU can only read an absolute voltage so that is why you must start out at a known value (150mV at the idle screw backed off).
Setting in the way I said in my previous post, the bike has excellent fuel economy and is running great with one exception - it sometimes does one "cough" when starting out from stopped. Also the cold start is a little hard - I have to rev it up for a couple seconds after starting or else it will die out. But this could be a leaky injector or something.