I'm 190 pounds w/o gear on, almost always have Jesse aluminum panniers on the bike, and have always had the preload on the stock shock spring at max and still felt I probably had too much sag. With any luggage at all, I had to use the manual lever on the headlight to keep from blinding oncoming drivers, even with the lights on low. Put The Girlfriend on and the spring was way overwhelmed.
Finally decided to do something about it. Really had a hard time finding spring options. AV_MECH worked with Sasquatch Suspension in Idaho and figured out new spring rates but that suspension guy is in jail now...
I took my own sag measurements and compared to what AV_MECH had for targets. The front was spot on which didn't surprise me as it's always felt about right. The rear had about 3/4" too much sag with no luggage.
HyperPro lists a spring kit but feedback I got from an inmate indicated it was really stiff. I exchanged some emails with Klaus (email@example.com) at EPM (which carries HyperPro in the US) and he shared that they have a progressive spring that fits the 800XC that would fall between the one listed in the kit and stock. He said the heavier spring is 141-212 N/mm and the next one down is 103-143 N/mm. I've seen some different numbers, but I think stock is around 100 N/mm straight rate.
I really wanted something heavier but didn't have time to do a bunch of experimenting since I'm leaving on a trip soon (tomorrow actually) so decided to try the 103-143. $139 for a purple one, $149 for black. I got black. Part number is SP-MO 1198.
My buddy Doug at the local KTM/Ducati shop helped me swap the springs. Unfortunately his spring compressor wouldn't work with the plastic sleeve the Triumph shock has so we had to go old school and use tie downs.
Note - if you're pulling the shock out, it helps immensely to pull off the shift linkage at the shift shaft and remove the countershaft sprocket cover.
My target sag with rider is a tick under 3". With me on the bike and no luggage, I ended up at 2.625" at max preload. I haven't measured it with everything loaded up but I think it's going to be about right. I did about 30 miles on it yesterday and it felt great. The whole attitude of the bike is better with the rear end up about an inch. The spring is going to end up still slightly soft with full luggage and a passenger, but it's definitely a step in the right direction.
On a side note, Race Tech didn't list anything for the 800, but I had sent them an email in early December to see if they had done any work yet. I got a response a couple of days ago (I had already bought and installed the HyperPro spring by then) that YES, they have products and settings for the Tiger 800's. Gold valves, springs, etc. Terry Diederichs (firstname.lastname@example.org) was the person that responded to me. So there may be some good options there as well.