Number 4
a fast throttle can also be dangerous:

Accident risk: A fast throttle can be dangerous in urban areas with traffic because it is very responsive.

Locking: If installed incorrectly, the throttle can lock.

tbh, i keep the money to upgrade bike.

but anyway, since its a used bike, you could replace all wear and tear part (eg kone bearing, wheel bearing etc), service all the item listed 1 - 3 and change to steel braided hose + each front caliper has their own brake line to master pump, that should provide better ride experience. Also consider steering damper as one of your mod.

Item no.4 subjective. if you having hard time to full throttle, then fast throttle could help that. It reduce the angle needed to get WOT.

Try spend more time ride aggressively before decide which part need upgrade.

Maybe can start with premiumcycle @ sunway, TakongRacing @ cheras or any big bike service center. Bought mine at Teguh Bikers @ kmpg Melayu Subang, alang2 replace my faulty masterpump.

the steering damper can find in shopee or performance bike shop, just need to pair it with mounting/bracket for XJ6/

I would just fix maintenance issues. Depending on the mileage of your bike, a good service, with new brake pads, fork service (rear stock monoshock might not be servisable).

It wont be worth the money to updrade an old bike....typically. You are better off saving money to your next bike. Those items you list dont come cheap especially good adjustable suspension components.

With your mods list, you can sink 10k into a 15k bike, which to me, a lot.

Instead, depending on what type of rides you do, spending more on good tyres, or luggage will give you added flexibility in what you can do with your bike.
Whats your reasoning to upgrading the items on your list?

You  going to track the bike?

Have you done sag measurements on the bike and set correct preload yet? If not do that first. Otherwise no point planning any mods first.

What do you find lacking on your brake and suspension currently that is motivating you to upgrade?

A more powerful  brake on a non abs bike ridden on the street in all weather might not exactly be a good thing.

you need 2 people to do the sag measurement. All you need is a tape measure, and the tools needed to adjust your preload, in this case your rear monoshock.
There are plenty of resources and videos online for proper sag setting.
What makes you say you need a harder monoshock? unless there is something wrong with the existing monoshock, or you are much heavier than average, the stock monoshock is usually sufficient for most riders.

If you think the rear monoshock is too soft and wobbly, it may have an issue with it, or something else can be off, like tyres, alignment, or maybe you need to ride within the bike's limits.
Even if you do buy a new monoshock, good suspension makers will also ask you for technical details, like spring weights and why your existing monoshock is not working for you so they can customize a set suitable to your requirements.

I've tried fast throttle on my XJ6 before, but found it quite uncomfortable in town because of how "keras" it feels to make small inputs, I took the rm 10 shopee domino fast throttle and modified the tube to fit the XJ6 housing

the front brakes are definitely lacking on this bike, mine has steel braided hoses and aftermarket master cylinder, u can buy those rm 15-30 ones for kapcai, make sure to roughly measure the length

I'm using a chinese master cylinder, the brand is Adelin, around rm 140 on shoppee, these wont really improve the braking power but the braking feel is soooo much better than the spongy standard setup

forks I havent really done anything besides 15w oil as not so many cheap aftermarket options haha

steering damper u will have to sendiri DIY the bracket, but the only times where my handle goyang is when im riding very aggresively 

Im not sure if im allowed to post shoppee links here  ,but here are the photos





If u want more peace of mind, u can get the RCB brake hose, but I havent really faced any issues with even the rm 10 unbranded hoses, my friend has been running them on a naza blade 650 with dual 4 pot calipers for over a year now, my XJ6 came with original Hel hoses, but the outer rubber coating gets rubbed off just as easily as the unbranded hoses if not routed properly.

The hoses with threaded fittings im not a big fan of as ive had them come loose and leaking on other bikes

The master cylinder I got the 17.5mm one but I think a 16mm is better so u wont have to put as much force on the lever to get the same amount of braking power

Have u guys even tried better brake pads like the ebc hh?

Having real good calipers, hoses n cylinders will still be bad if paired.with pads that dont bite

Not sure of urs is the correct year

https://www.ebay.com/itm/141807287741

I get mine from the same seller for both my bikes.

Some shops do sell ebc pads.... Like 66speedbike in sg buloh..but ready stock or not for ur model..have to check with them.

I just order from ebay n diy pasang...takes abt 2 weeks to arrive.

Whether u get taxed when it enters the country depends on ur luck..ive never been taxed after multiple orders of brake pads....but another forumer got taxed for pads which was shocking to me (he bought from.diff seller iirc)

Anyway...for both bikes n cars...if wanna mod brake, should always do pads first as they r pretty cheap n r the main friction material....if still not enough for ur type of riding, then only think abt other components. N honestly, even for some casual track day riders, a simple pad upgrade is actually enough

U can find EBC pads at FTZone Penang, U can find the shop owners number on google and pm him 👍