Improves airflow up to 92 Percent. Nearly doubles flow. 4 - inch constant - diameter downpipe - back system with Straight - through muffler. Easy install. Tip optional. Compatible with factory warranty. Monster Performance Modest Price. Banks' new Monster Sport Exhaust is one cool system And its low price That's way cool. The system slashes backpressure, increases exhaust flow, improves fuel economy and delivers extra power to your rear wheels. Exhaust tip optional. 4 inch constant - diameter exhaust system. Virtually eliminates backpressure nearly doubles the flow Lowers exhaust gas temps. Straight - through Monster Muffler delivers a commanding exhaust note. 100 Stainless Steel. Easy install. 5 inch rolled - edge polished tip is optional. Fully compatible with the Ford factory warranty. 5 - Year Limited Warranty.