You can do the 1800 seat mod. You just buy a seat from a 1800 and modify it to fit your 1300, and then you can have a solo or use the passinger seat to. You can find used seats for sale on here or on ebay. Otherwise if you want something different you can get almost any aftermarket seat solo.
Firedog, I went with a Mustang Vintage solo seat. I love it. It is so much better than stock. I could go maybe 30 mins with the stock seat before butt-burn started setting in. The mustang seat was great from the start. I didn't even need to break it in. I have never even thought about my seat since getting the Mustang. It's way better and I highly recommend it.
I don't believe the So Cal Slammer or Solo are in production any longer.
The original So Cal Cycle Seats is out of business. Their old website
(www.socalcycleseats.com) takesyou here: http://www.looneyseats.com/ and that appears to be a
Massachusetts based business. Rumor I heard was that a patented
seatpan was being used with no royalties having been paid to the patent
holder. I have no idea if that's true.
There's a new So Cal Motorcycle Seats out of California at this web
site: http://www.socalmcseats.com/ and you don't find either the
Slammer or Solo listed on that website.
I love my So Cal Arizona (Slammer) for local cruising, but it's not
comfortable for long rides. I have a 2nd seat for that.
I dealt with Mike Miller who recovered my Arizona/Slammer. I have no
idea where Mike ended up, but he was great to deal with. Anyone know
where Miller is?
I've got both the SoCal Slammer and the Ultimate Low Rider.
Like was said before, the Slammer isn't comfortable enough for long rides but was the lowest seat make for the 1300 VTX.
Check out my album to see pictures of both.