The Flo-Pro muffler I bought for my 06 is very quiet also. Too quiet actually so I went back to straight pipe but for someone who wants a good flowing and barely louder than stock sound I would suggest looking into Flo-Pro. The muffler was $100 by the way.
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2006 Dodge 2500 4x4 QC Auto Smarty Sr. S&B C.A.I.,CAT MIA,FLO PRO Muffler. Autometer Gauges
2003 Dodge 3500 4x4 quad cab auto (all stock)