The Hagon shock comes set up like the standard Triumph shock on minimum pre-load. It worked well straight out of the box for me. The damping is adjusted by an Allen Key which they supply.
Being a shortie I left the spring as standard and increased the damping by a quarter turn after about 500 miles. I have since ridden 4,000 miles on the same settings.
I'm sure you will not regret buying the shock. On my website I refer to the fact that when replacing the shock I found it much easier to remove the top shock mount and the swinging arm pivot bolt, then withdraw the old shock and swinging arm together. I had a real job removing the lower shock mount which proved to be a very tight fit. Best of luck with the lump hammer!