Other than the tiny amount of pully inertia and friction, it is drawing nothing from the engine at WOT because the clutch disengages. Under normal circumstances I would guess 2 to 3 hp, but that is purely a guess.
2013 Red Candy Metallic GT Premium Coupe
Black Leather, 6MT, Comfort Package, Brembo Package, 3.55 Axle
Borla Touring axle back, Suntec CXP 45% window tint, Eibach Pro-Kit, Steeda Strut Mounts, Rear Upper Control Arm and Panhard Bar, BMR Relocation Brackets, Energy Suspension Shifter Bushing