I recently installed a dual 3.5" exhaust on my Nissan Titan and the drone was pathetic. I love my truck, but driving it was a chore. I put one of these in each exhaust pipe and it drastically reduced the rumble and volume. They are very strong, in fact it took a few hard hits with a hammer. Using a decibel app reduced my in-car readings by 7 or 8 decibels. The only reason I knocked the sprocket off is because I now hear a whistle coming out of the exhaust pipe at higher rpm, but it's not too noticeable. It probably wouldn't be a problem if I placed them above the exhaust system. Overall they work great!