After doing a bunch of reading and listening on Youtube, Flowmaster 50 Delta sounds about right. Next is to do some research on a couple other brands and then decide.

 

Get ready to have massive drone riding down the road...

 

Wrong ^^^ I have 40 series original on a 351w and the interior resonance is minimal, only hear it with the radio turned way down. 50 series delta is a quieter muffler so even less resonance, people who have problems with too much interior resonance (drone) are usually the ones who did not use proper hangars.

 

Also, the farther away from the cab that the muffler is mounted the less resonance you will have, mines under the bed. If its mounted under the cab there will be more.

 

Mine will be under the bed too.

 

I'm keeping that in mind while I'm doing my research. The 40 series Flowmaster seemed louder than I wanted, so I am looking at the 50s. I still plan to look into Magnaflow before I decide.

 

Magnaflow is overpriced in my opinion. With your system hanging on proper rubber hangars it will sound great.