Good questions here...
First of all I want to mention that the full Parts Canada, Motovan and other books (the same ones bike shops use) are all available online.
They're exact, page numbers, everything. A valuable resource but many are not aware...
There are pages and pages of front suspension stuff - top quality, big brand-names - but they don't get so much attention.
In the shop, the pages are clean and not at all worn out! Because most people balk at the prices...
1) Springs. Very unlikely that your ride comes with the right springs for you. Plus, they wear out and 'sag' over time.
Good aftermarket springs can be higher-quality (a superior spring-steel) and higher-tech ie. progressive etc.
2) Valve kits are attractive if your stock forks suck. If your ride is built to a price point, non-adjustable, inexpensive, or of course old and worn-out too - you can re-valve.
3) Cartridge kits are obviously the Real Deal - a high-end upgrade for those with a taste for the good stuff (and the wallet to make it happen).
You can spend a lot of money on good suspension...
The Cycle World magazine guys down in California had an interesting debate.
They compared the new FZ09 triple ($8k) with the Triumph Street Triple R ($10k).
Buddy spent $2k on suspension and this & that, trying to make the Yamaha handle better...
But they observed that it still was not the equal of the Street Triple (though he had effectively spent the same).
JC100, springs are a no-brainer - especially if you're a big lad or whatever - and won't break the bank.
You don't need to do 1 and 2 together but could do either/or.
Springs are 'the foundation' IOW you're building the house on them, y'know? They're fundamental.
Valve kits would be to repair, or to upgrade if you're the owner of suckage. Tiger 1050 forks are probably okay and better than most...
So upgrade your springs and regroup - see where you're at.
Fork tuning can be accomplished with different oil. Fresh, trick, expensive oil (maybe in a different viscosity) can work wonders...
Like a whole new fork! But beyond that (somewhat limited) adjustment variability you're looking at new fork valve kits.
And of course Cartridge kits are for the bike you love, you adore, that you're gonna keep 'forever' and that deserves the whole 'prestige' scenario.
HEAVY bragging rights with yer buddies, heheh...
Hope this helps,
Regards
