I love these Borla mufflers. They start out a little louder than the factory mufflers and die off within a minute on factory mufflers. They don't get much louder in normal driving, but once you get behind the wheel they really come alive with a clear, non-cloying sound. I used 40659 on my old 4 cylinder Elantra and it was great, my car didn't even sound like a herbivore. When it came time to upgrade my exhaust on my LF Sonata, only one Borla came to mind. These mufflers are loud when they'reβ¦