I have a 3" maddad whisper on a bugeye wagon (207 uel headers) w/catted stromung midpipe, catless stromung dp. It drones way too much on the highway and is slightly louder than desirable at cold idle.
I'll be swapping to EL twin scroll and adding a helmholtz resonator for the drone. You can make one or see this product (
http://my.prostreetonline.com/2014/0...ne-resonators/)
If that's not quiet enough will also add an oval straight through resonator and matt the wagon back.