I had 204s in a 11 SG and really liked them. They pulled hard but not until a little higher RPM. In my 12 Limited I have the 585s and love them. I have some additional work done but they come on early about 2,000rpm. A friend has the same set up as I do with 259s and he can't touch me on the start and I get far enough ahead that he has problems catching up, he rides a 15 RGS.

 

I'm extremely happy with the 204's in my Road King even with true duals. I have S&S 511's in the limited. Those are higher end and will really move the limited at higher RPM but not my riding style. The 204's come on much earlier and seem to give it more torque.

I agree with earlier posts, if you want more low end torque, consider changing your exhaust. A good 2 into 1 or 2-1-2 will give you a little more low end.

Good luck!