Indy,
The sound difference is noticeable at idle, a little deeper, but very noticeable when you get on the pipe. I really like it that way, so the bike is somewhat quite when gently cruising, but has a really nice sound when you get on it. If you want it louder at idle, I would go with a little more open pipe.
The power on the other hand is very noticeable. It is producing the 100 ft of torque at about 2500 rpm. It is great on the torque end!! I was looking to change cams so I could get the hp up a little more. My last bike was 105hp, and it was awewome to crackt he throttle on the open road and let her rip! to go up to the 251 cam I want to put in the bike, my dealer says I really should put heads on as well. The upgraded cam on the SE is the 203. Without heads I could only go to the 211 which wouldn't be much of a difference for the cost.
Therfore...I think next spring I am going with the CNC Ported HTCC heads. That would allow me to go all the way up to Harley's 260 cam, although I think I am going to stick with the 251. From what I understand the 260 cam is all high end hp and not low end torque the 251 is a good mix of both from what the dealer can tell from the few they have put on this spring, since HD came out with that cam.
I am/would be changing the cam purely for performance reasons, although that loping sound at idle is a great bonus. My last bike was a Deuce upgraded to 95 cu. in with the 257 cam, HD's regular performance heads and Python pipes. The sound at idle was simply awesome, but when you opened it up it was a bit loud.
So hopefully the combination I'm trying to put together this time will give me all the performance I'm looking for with a good, yet tolerable sound level.
Andy