07Mustang_On_18s

even with a decent muffler?

oi8achevy

i have worked for a company that designed and built them. you have to be making some serious hp before the cats become a restriction to airflow. thats why they make them larger in diameter than the pipe. and they do help clean up the harshness of an open exhaust.

amptor

I talked to a mechanic who has been in the trade for 35 years and he told me once that #1 emissions equipment on modern vehicles is designed to operate with the engine and removing it can decrease performance, and later on he told me that cats dampen sound which is why my sister's old fiero is so loud (needs a new cat).