I put an 18inch magnaflow on my 2012 ram express about 1 mounth ago and when i first put it on it sounded great. Now that it's been a while it seems like the sound inside the cab has gotten quite and to me that it should be getting louder. Also when i am parked and if i rev my engine up i get a burnt smell, it almost smells like a break in smell of some sort. I may just may be getting worried for nothing, but figured i would post and see if anyone else experienced this.
Break in smell, have had mine on for about a month, it did that at first till I did a huge ride of around 500klm, now I never notice any smell. As for the sound, it always sounds the same for me, cab sound and stomp on the gas sound, nothing different over time, is it a slap in model by mufflex or and weld in unit by magnaflow? mine is a mufflex bolt in, after a week or so, best to check your clamps that they be tight.