Most important first:
I did the 105/kt7 set into 2021 Duke 390
HIGHT/LENGTH: I thought the bike was twitchy as it came, so I had raised the triple-tree to the top of the fork tube. After the install the total length of the forks is about 10mm longer, so i put it back two lines down (looks like stock, is actually +10, which is my preference). It looks like you could drop another 10 and still get a cut-off Allen key in there. If you want to get lower buy clip-ons that rise enough to fit over the bodywork.
Stock was pretty good, but I did get an unwanted bounce when doing stoppies, which IMHO indicates under-damping. If you're watching costs it might do the trick just to swap for heavier oil as a starting point.
Did NOT have to separate the fork legs, nor detach the leg bottom. Save yourself buying the seal driver ($55), fork leg holding tool ($?), Pin wrench ($?), and a bunch of work. Save yourself the bleeder tool ($60) by buying a long m10, thread pitch 1 bolt and some nuts- lock the nuts together with some naked thread (female side) showing, can draw the bleed shaft for like $5.
I'm glad that I read this thread before installing; I got 1 bottle of 5w oil, and 1 of 10w: 5 goes in compression side, 10 goes in rebound. At this time it is already less bouncy than stock and I have the adjuster still all the way out from install (haven't tuned yet)
extra long m7 Allen (socket is best, as it takes quite a bit of force to loosen) for fork leg bottom bolts
24mm socket or wrench for stock fork caps
25mm socket wrench for new fork caps
17mm open end wrench for the preload adjuster and damping rod top nut
Bolt: m10 by 25 long, pitch 1, hopefully included with kit
m4 Allen, probably cut short, for adjustments once everything is installed
spring compressor, cheap one works ($25)
MOTORCYCLE FORK SPRING COMPRESSOR KIT, UNIVERSAL, VinGence https://a.co/d/hr9lDTA
Do what I say, not what I did. Suffice it to say the job took me longer than it should have.
Get the front off the ground. The method of lifting is left as an exorcise for the reader.
Remove the front wheel.
For access to the original fork top caps you may need to remove the handlebar hold down plate
Turn the steering all the way left to hold the forks in place, then loosen (not remove) the fork caps
Loosen the fork pinch bolts and smoothly/gently slide them out, placing them on your nice padded bench in your nice heated/AC'd garage... Hahahaha.
Use the axle half-inserted and the long Allen socket to loosen (not remove) the bottom bolts.
Remove original cartridges and drain the oil. There are multiple ways to do this: I would recommend turning the fork upside down over a pan, removing the bottom bolt, then removing the "top caps"- actually the whole cartridge, and having everything pour out the tops.
reassemble in the reverse order as disassembly, and in accordance with the Andreani instructions. Note that the rebound leg requires the special bolt. I (and this thread) recommend heavier oil. Also adjust the fork height, while bearing in mind the ~+10mm total length.