In these things I am always stunned that such small numbers make such a big difference. The difference in the area covered by a 1.72" valve and a 1.84" valve is 0.3357 of a square inch. The difference in the circumference is 0.377" and diameter 0.12".
So where the difference comes is in how much more fuel mixture can flow through the larger hole doing the time the piston is on the intake stroke and the intake valve is open. Velocity is important to both move enough mixture[to fill the cylinder and to keep it mixed. If the new hole is too big the velocity can fall off.
I don't think it can work. These things are just a fad that won't last.
