This Bass Booster Port Kit provides significant improvements in bass response without adding a subwoofer and has no impact on useable Tour-Pak carrier cargo capacity. When installed, the open port permits the speaker pod to "breathe," reducing the compression effect that limits speaker cone travel. You hear a 21% increase in bass response for better sound with a fuller bottom end and an 82% reduction in peak distortion for accurate bass reproduction. Noticeable improvement is gained with both Original Equipment and Boom! Audio High Performance Speakers. The kit contains black-anodized aluminum ports, stainless steel audio-transparent grills and unique Sound Sealing technology to give you that Boom! you were looking for.