I have the Rinehart 4in slip-ons. I've had the true duals and 3 in Rineharts. They sounded great, but you're right, they do get a little loud after a while. The 4's give me a good low rumble sound, but no blare if that makes since. The thing with Rineharts, you can always sell them.
2013 Ember Red Street Glide
2012 Tequilla Sunrise Road King Classic
2005 Sunburst Yellow Screamin Eagle Electra Glide
2006 Cobalt Blue Street Glide
1998 Tangerine and birch Heritage Softail
and more Hondas than I can remember. 2