Glasspack mufflers do not have extra sound-absorbing material. So, in order to absorb sound, they use the glass layer and packing. But if you are making your order on partcatalog.com, you can always inquire about the recommended tube diameter for your exhaust system by providing your make and model. This can lead to a significant decrease in torque and horsepower as well as rpm.

Considering cat-back exhausts replace more restrictions, they typically offer increased performance and noise compared to axle-back systems