Most everyone here including myself have changed the front sprocket to an 18 or 19 tooth and kept the rear sprocket stock. At least thats what I did with a 19 tooth front.
I added progressive spring shocks to the rear and added progressive springs to my forks. I used Ikon products on mine but a lot of guys here can inform you about the other products.
I'm very pleased with my setup. I fractured my L4 vertebra back in 1990 and live with back problems but none I equate to my bike. I've hit some hard dips but my suspension does it's job for me.
I've got a 06 America with the same engine as yours and the 19 tooth sprocket worked out just fine.
BTW, welcome to bonnevilleamerica.com. There are tons of information on this site that you will find useful.
