Recently installed Roush axle backs and am pleased with the sound. However I was wondering if the popping sound they make means the engine is running rich and could be harmful to the car. Any feedback would be appreciated.

 

Sounds normal with many different style axle backs.

 

Just put ford racing axle backs on this weekend. They have a GREAT sound, but pop and crackle like crazy when I'm decelerating and holding a gear. I don't think it's an issue at all...just back pressure in the exhaust system.