So I've been toying around with this idea even though I know that it's impossible to execute safely:

Let's say we fill the boiler of my Lusso all the way to the top. We remove the pressurestat and replace it with a cap through which a thermocouple passes, the other end of which is attached to a PID or temperature readout (allowing us to be a manual PID by switching the machine on and off appropriately to keep the temperature regulated). We remove the OPV in the top of the boiler and cap that off. We open the water wand and attach the output of a vibration pump to it. In this example, we could have my Gaggia Espresso sitting next to the Lusso and have the Gaggia reservoir filled with water (and the pump output attached to the open hot water wand, passing a 9bar regulated OPV first). To pull a shot, we pull the lever down and then start the pump, allowing us to get as much volume as we need. When the shot is almost done, we turn off the pump and finish the shot's last half ounce with the lever pressure (if this makes sense for the taste).

I can think of several problems with this, including, but not limited to, exploding boiler, exploding pipes, and severe burns from being blasted with 200F water. I cannot recommend that anyone attempt such a modification as it seems very unsafe.

Disclaimers aside, what are the chances that it would work? None? Slim to none? Slightly possible?

Could there theoretically be a significant taste difference from other pump machines due to the column of water in the group?

Where does the brewed coffee go that does not end up in the cup? There's no three way valve or even the spring loaded group valve of home machines to prevent it from going back into the boiler.

Exploding pressure vessels and pipes are a minor problem for any dedicated hobbyist, but this is major.

Same place as it does with normal lever operation: out through the portafilter. At the end of the shot, the spring would close off the boiler and force the rest of the water in the group down through the coffee.

Oh wait... if we're making a 9bar shot, then it would probably choke the spring... How about hoping that the spring at least seals off the boiler, then slowly cranking off the portafilter and letting the water drain (explode) past the PF ears?

Or we could ruin the group by drilling in a three-way valve?

Good catch there, Jim.

But what would your gain with that? The PV Lusso group is tuned to a temperature difference between it and the boiler. That temperature difference facilitates steaming.
With your thought experiment you'd lose the steaming ability and end up with cold, sour espresso.
There are other ways to make dangerous things.

Do I understand this correctly? You intend to increase the boiler pressure by a factor of 6 Don't tell Home Land Security because you may have reinvented the "pipe bomb"

Just kidding about the pipe bomb. But seriously I doubt that boiler is designed or built for a pressure of 9 bar.

Take care
Geoffrey