I did notice a change in the sound of my magnaflow after running it for a few weeks. It got a little louder but not too much.

 

I noticed a sound change in mine as well after it was on there awhile, but my 14" still isn't really loud at idle.

 

ya it just takes a little bit of time. i noticed a big change after about 5000mi.

 

Same here, my 22" magnaflow is still not that loud at idle even with LT's and a cam. But it does have good sound if you get on the gas.

 

I have true dual magnaflows and they sound nothing like stock and they sound the same rather they are hot or cold. I have the 5.7 hemi. They also sound really good at idle

 

Thanks guys. Everything forward of the muffler is still stock. Just something I have noticed about it and wanted to see if anyone else noticed the same thing. After the truck runs 15 minutes or so the sound is awesome, nothing like stock at idle or accelaration, it is quieter at idle though which was part of my decision to go with Magnaflow. I guess it just boils down to letting the truck warm up.

 

I have the same 12258 on my truck but i have a hemi, i don't find its all that quiet when i first start it up although it is not terribly loud, i have had mine for a little over a year now and haven't really noticed much of a change in the tone, i think the only way it will get any louder were if the inside rusted out but being a strait through design i still dont think it would make much difference

 

I have the 30" Magna flow and it has a nice beep rumble, no drone and is quieter than the raspy FM50. As for a breakin period, I have heard nothing about that with Magnaflws. But on my VTX 1800 I put a glass pack style muffler on it and the factory said the muffler was constructed withe glass material inside a plastic bag for ease of installatio and during the breakin the plastic would be burned away and the muffler tone would change. Maybe something similar happens with the Magnaflow. I hope not as I like mine the way it is.

 

About a month ago I had the stock muffler replaced with a magnaflow having it exit infront of the rear tire, yeah it did sound stock at first but after a few weeks the sound changed and just recently I got a tip for it and it sounds great!. Just the sound my truck should have, just wait a bit depends how much times you floor it and what not. Adding a tip imcreases the sound too, atleast mine did

 

Temp should have no effect on the noise other than the truck is running richer and usually smoother when cold.
Mine got a little louder after about a month or so of driving once the packing got settled in.