IPD Plenums provide a simple, yet highly effective way to gain extra horsepower and torque for improved acceleration. Featuring a new designed aluminum plenum which replaces the flat-walled stock plenum with a design that increases airflow and air speed (velocity) to the engine. Dyno tests on a 1999 Porsche 996 revealed a 28 Horsepower increase and 26 ft lbs. torque at the rear wheels.