1320 Performance Patent Pending Ultra Quiet quarter wavelength Resonators have become the preferred choice of exhaust fabrication professionals looking to effectively reduce exhaust noise and drone from their performance exhaust setup Our QW design have been proven to reduce 18-22% more drone than standard none QW design. Each Quarter Wavelength resonator features straight through design to reduce back pressure. Our resonator are densely packed with our premium multi-layered sound absorption materials & PREMIUM 304 Stainless Steel construction, polished to a beautiful mirror finish.