You'd lose torque and move your powerband wayyyyyyy up in the RPM range... but you would 'technically' see a horsepower benefit to it by uncapping the exhaust like that. That's why you see top fuel drag cars with four pipes on either side immediately exiting the cylinder heads... no backpressure = more power up top... they've got too much torque as it is.

For this application, I do believe this is what you'd call 'idiotic'.