I just installed a flowmaster 70 muffler this weekend. Part#53071. I was a bit nervous because I don't want loud, but all is good. It is very close to stock in sound, with just a bit more rumble-y undertone. Haven't had it on the highway yet (that will be this afternoon) but don't expect anything unpleasant.

Had to change it because my old muffler has had an internal vibration that would last for a few kms after cold start up since I bought it. Recently it got worse and I just couldn't hack it anymore. So I hacked it - OFF- and now I'm happy.

I had an FM70 before on my old 94 with a Magnaflow cat and that truck was too loud for me. Family and friends would just shake their heads. It is obvious to me that the difference is the cat. The stock cat mutes a lot of the sound.

FYI - running the 70 without a tailpipe made the truck a lot louder. I was worried that I had made a mistake. But the tailpipe took away all of that noise.

 

I like mine, its a good compromise between the stock sound and a little rumble. And a little more performance.

 

That would be too quiet for me. I like my original 40 series.