I have used a Corbin seat since 2010. Have the back rest and back rest for my wife. Hated the Harley seat on my 09 Triglide. Tried to get a Mustang seat for the trike, but whoever I talked to at Mustang said that they didn't make a seat for the Triglide and they weren't going to.
I called the main office at Corbin and they sent one right out. Yes it was a little hard, but they said it took 2000 miles to get it broke in to fit you. They were pretty well right and now I love the seat. It is very comfortable. Can ride all day and doesn't bother me at all. Wife likes her backrest because it has longer arms than the Harley original. The only regret I have is that I didn't get the heated seat.