You're not ignorant. They are inexpensive muffler inserts (sometimes called lollipops) that can (maybe not always) increase low end torque a little and deepen the voice of the exhaust without making it louder. They are Thunder Torque Inserts and are sold by TK Custom Cycles:

Hope this helps.Thunder Torque Inserts - FAQ

 

FYI: sold by DK Customs.

 

Got in some sheets of glass wool to wrap the baffles for that deeper bass . Now to pull the baffles and tti to wrap the baffles.

 

I have been sitting around and wishing I had the wiring down on my 2000 sportster instead of working on the wiring.

 

The universal bracket that came on my seat always bothered me a little. So I finally made another one.

 

http://www.dkcustomproducts.com/thun...dk-tti-158.htm

 

Okay, I am familiar with them called "lolli-pops".......

 

I put some Leatherworks saddlebags on it.

 

Apparently, these are better engineered than the flat ones and do a better job. As I said earlier, I am very pleased with mine.

 

love the bags , if you don't mind....where did you get them