Instantly increase turbo response and add 15-20 wheel horsepower and 20 ft-lbs of torque with the PERRIN Equal Length Headers. This part is perfectly safe to install and does not required an ECU tune. Dyno graph shows results of a 2015 WRX with typical bolt-ons (3 inch turbo-back exhaust and no ECU tune) where the PERRIN Header was the only part changed. This test was performed with an hour between runs.