Are you thinking about putting a Sundowner Seat on your 09-11 SG? Well here's my opinion and findings:

I bought the Sundowner seat (PN 51630-09A) for my 09 SG. I tried a Mustang seat as well but found that it pushed me forward and raised me up (about an inch or so in both directions). I'm 5'10 and like the stock seat position.
The Sundowner, I feel like I'm in the stock height but maybe a tad lower and maybe back an inch. I feel like I'm actually sitting in the seat and have back support without the back rest. My wife really loves it. As far as comfort goes for me, I'm thinking I'll like it more after it's broken in.
I've accepted the fact that I have to sacrifice looks for comfort (more the wife's than mine). The rear portion of the seat is huge compared to stock. It will rub the side covers in two spots on each side (cover those spots with clear protective tape). It doesn't reveal the scuffs on the gas tank that are left by the stock seat. If you have the passenger back rest, you'll have to remove it to install and remove this seat. The rear of the seat covers about a half inch of the bottom of the back rest. My rider's back rest fits with it perfectly.
I bought mine from Zannotti's for around $280 shipped versus going to my local dealership and paying $329 plus 9.75% sales tax...
If your looking for a new seat, I hope this helps with your research.

 

Thanks Dude. Being seat shopping for the bride. On my 07 RK Mine is ok. Not great after a couple hundred miles but I can live with it. She on the other hand says no more trips until I change it. Come to think of it might not ever change it. LOL.
Rev

 

Since I posted this, I've put about 6k miles or so on this seat. I don't like it. After about 100 miles I feel like I'm sitting on the seat pan. My wife loves it so I guess I'll be getting it modified this winter.

 

Some gel and better foam from a custom seat builder will go a log way. Thanks for the report. I have the Sundowner and will have the mods made to it as well.

 

It's funny how subjective seats can be. I bought a Sundowner mainly for the wifes comfort. It was the most comfortable seat I've had, but the wife didn't like it. I could feel her sliding forward every bump and every time I braked. She would have to always move back to keep from pushing me up on the tank.

I ended up with a stock FLH seat. She loves it that seat. I've got to use the air hawke though.

 

Yup, seat comfort is very subjective. I've got the heated version of the Sundowner and still love it after nearly 20,000 miles.