What did they help with ?

 

Low end torque.
They might have helped more than that but I didn't try.

When I first put on the fishtails (no baffles) I took them for a test ride that lasted a 1/4 mile before I took them off in disgust.

After I put the aftermarket baffles in all was right with the world again.

 

FWIW, when I bought my Heritage it was loud and lacked low end end torque despite appearing to be bone stock at first glance. Closer inspection revealed that even though it was the stock exhaust system with the crossover pipe, there were no baffles in the mufflers. I called Big City Thunder and installed their lollipop style baffles at the end of each head pipe just ahead of the mufflers. The sound got a lot a deeper, my torque was restored, and yet it was still loud enough to sound like an Evo should sound.

Even after I did the cam and all the rest of the engine refresh a couple of years ago, I kept that same exhaust setup since I liked it instead of spending ,only on something that I may or may not like.

Interestingly enough, I have taken an interest in the last few days of listening to a lot of Harley exhaust videos in YouTube and found RC Components slip ons not only sound good, but their torque and horsepower numbers were also great. They are not as popular as Vance & Hines or many of the others, but on the videos I watched, they made better numbers and had a much deeper, less raspy tin sound than the more popular brands. Rinehart came in second in my opinion got sound quality. Large diameter Vance & Hines sounded good but the smaller the diameter, the more raspy, harsh, and tin sounding they were. Rush large diameter slip ons exhibited the same characteristics.

Here is a link to RC Components. They have numerous tip styles.

http://www.rccomponents.com/rcxhaust.htm