It's not necessarily like "how many HP will I gain by doing this or that?"
A very well tuned engine works like an orchestra. Each piece works in tune and rhythm with each other piece to make beautiful (in this case 2 stroke) harmony. If one instrument is out of tune most people wouldn't be able to single it out or maybe even notice but they might notice that the song isn't as crisp and clean (or in this case powerful) as one that is all working together 100%.
The analogy here is using the stock carburetor on a massive built engine. Normally, however, it's not that simply to single out one item which is the obvious deficiency.... it's more like a little thing "holding it back" here and there and they add up to the "tune" of an engine.
A vito's BBK on a stroker crank properly ported with the right pipe on pump gas will make probably ~40 hp. If you change one single thing on that it may affect that number some but it's not going to change it a whole lot.
The main thing to consider here is your intended use of this quad and your final budget. Now, half your expectations or double your budget. That's what you're actually going to get "in the real world". If you are willing to run high octane fuel in this engine, the engine builder can specifically raise your BMEP when they cut the head and you can advance your timing a bit to get some more power out of it. How much? who knows.... could be worth 2 horsepower, could be worth 10 horsepower.
To answer your question of potential power... I'm anticipating just northwards of 70 hp out of a blaster engine. That requires a LOT of concessions on the part of the rider and builder (no suspension, "bible paper thin" powerband, and potentially a lot of breakages) and also some pretty exotic (read: expensive!) fuel blends. I decided to make those concessions based on my desire to build a drag racing blaster that could be the most it could be..... what kind of concessions are you willing to make?
