Hi mate and welcome have a nice time here.
Regarding the suspension there are few things that can be done: use the OEM forks and rear shock and put just new springs, there are few good manufacturers like ohlins and hyperpro. This will change the bike feeling a lot. On the other hand you can buy a aftermarket rear shock and use YZ forks - will need some rework but nothing major. Here you can find few threads on the topic. Even I have seen a fella fitting Kawasaki KDX 650 forks to XT, which worked perfect.

Hope this helps.

Enjoy.

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that is how i feel about my XTR
Mods so far:
Hyperpro front springs; Hyperpro rear shock spring; modified air box; LED tail light; LED indicators + new relay; YZ pegs; Lucas aluminum bar; brisk spark plug; snorkel removed; DNA stage 1; second hand DynoJet O2 mod; crash bars; front and rear steel braided brake lines; soft EBC brake pads; mitas 07 tyres, 2in1 Metal Mule exhaust, Blocked AIS, tall OEM screen, OTR bash plate