That intake is built for a torque peak in the mid 5s with top power in the mid 7K range and a rev limit a bit over 8K.

Yes the butterfly is a hindrance to flow and power. Plenty of testing with barrel throttles have shown almost 2 Hp gain on a 300Hp 4 cylinder. I gave allot of thought to barrel throttles on the little 4G92 Mivec engine I am installing in a track car, then decided I do not have the time to make them so that project has a similar intake to the Starion one pictured previously.
These are built to gain throttle response, the big goal is throttle sensitivity around the torque peak allowing for the best balance control in mid corner. A single throttle plate with plenum just does not have the sensitivity, this is fine in a FWD car where you balance the car with the brake pedal but a RWD car is balanced with the throttle. Then again many drivers are better off with a single throttle so they will be less prone to unbalance the car.
With this in mind, a nice big single throttle is great for drag racers.
Here are some pics of the 4G92 Mitsubishi, this is a 174HP 1600cc engine from 1992. We surly did not get these stateside. I am converting this engine to a RWD configuration.






Now wait till I get a bit more done on a 6G72 ITB intake I am building.