Hey everyone, so I ran the flowmaster super 40 on my truck for several years and was quite happy with it. I decided to go a little louder and upgrade to the super 10. I cut my muffler off and drive around with straight pipe for a few days just to try it out. A few days later I jacked up the back end and put the new muffler on, I started and was greatly disappointed with how quiet it was. I took the muffler off and day later and couldn't believe how quiet it was. I ran some cat cleaner in my next tank of gas to see if some how in the install something could've clogged my cars but I'm still scratching my head. Any ideas?

 

The 40 might've gotten louder over time and you're now comparing an old 40 to a new 10.
You did install in in the correct flow direction I assume?

 

I triple checked the right orientation, and then took the muffler completely off. Now it's completely straight pipe and quieter then it was with the super 40.

 

As odd as it might seem, the muffler alters the resonant frequency which can give the appearance of being louder or softer depending on each person's hearing ability and range. The only way to accurately gauge the difference in sound level is with a sound meter.

 

Sounds like you have stopped-up cat converters.