Just had Flowmaster 40s installed (120 total installation) and when I first started her up I must admit, I thought it sounded kinda quiet. After driving it for two days it has definitely gotten louder, and I love it. What is the typical break in period for new mufflers? Will they get much louder?

 

They do "break in", as you say, it's just hte chambers going through heat cycles that breaks them in. It probably won't get much louder than it is now, maybe a few decibals is my guess.

 

Mine actually went the other way. They started out loud and raspy as hell but they mellowed out to a nice deep sound that's only loud when I get on it after about 500 miles.

 

My 40's series is on the 3100 engine so its not even as loud as most, but when I hit about 2500-3000 rpms it gives that nice deep sound I'm looking for. At first it wasn't as loud, but I was use to hearing the holes in the old muffler so that might've fogged my hearing.

 

x2 on the mellowing out...

I've heard that your exhaust note will be higher for the first 500 miles or so, then get a little nicer.

 

Give it a few months and Mike will know first hand!!

 

i have had my 40;s on my 3.5 for a few months now and they got a nice deep tone to them and it sounds really good

 

when i put the muffler on my truck it took about 1000 miles before it mellowed out & got the sound it has now, & the monte is still changing a lil bit

 

I would not say they get much louder at all...But the sound will change, as the break in. Mine sounded better after it broke in than it did in the first few hundred miles, maybe even first 2,000 miles to be honest. Mine had more of a tone, and throaty growl after break in.

 

I can not wait for my stupid thing to ship!!! Hopefully I get it on last weekend of the month!