A. better if u standby 5k. depends on wear and tear parts and luck.
B. EX5! haha..but seriously DOHC L5 or L6 with manual gearbox but spare parts a bit expensive
C. more or less same for 1 and second gear after that manual gearbox will hav advantage.

just my 2 cents. mayb other wan to share their experience?

hmm.. hardly see any auto gear box with turbo charged.. my friend modded his kancil with L2 engine combine with a good manual gearbox which can make the car achieve 160km/h easily.. all i can say is manual gear box is easily customizeable and cheaper..

Am using 660 kancil.. Hate the short gear change and low final gear..

Not timing but the ratio. More teeth or less teeth. For 850 the standard gear ratio is 1st gear 3.500, 2nd gear 2.111, 3rd gear 1.392, 4th gear 0.971 and 5th gear 0.794 and for 660s the ratio respectively , Hey! they are the same    Only the reverse and final ratio lari a bit.

That means the gear  box is usable on both models. To change the gear ratios you have to dismantle the whole gear box and the labour charges very expensive. I repaired a Rusa gearbox once(no potong kereta) and change the syncromesh and 1 gear and it cost me over 2K

New gear box for Rusa, almost 4K plus labour   Not mistaken same gearbox as Avanza.

Both 850 and 660 will reach 110kmh at 4200RPM but will take 660 to attain it in longer time. The same block only different bore and stroke. Difference is 850 has a higher torque. I used to lower the front springs by 2inch in my former 660 and I though of doing it on my 850 now. It turns corner  better.

Lol.. Hardly find people drive first batch in this forum.. my car are stock.. Even the original GX sticker and Perodua sticker still on.. Just the rim cover change to 2nd gen.. because one of the stock rim cover flew off..
My kancil final gear still can tailgate vios auto at 100km/h.. If manual vios cant lar.. I can feel there is still extra force when it hit 100km/h.. Thats why i want to know the RPM at that speed..

Yalorr! because if you look from the side Kancil front is like higher than the back, like 'conggang' lidat!   So, to level the car back, I lowered the front only.

Hello!
Stock engine i normally advice not to change. Better save that cash up for other things.
Only unless you really want to la. hhahaha. S-flow i hear is ok for auto and dont go bigger than 1.8inch pipe.

Here are some tips to make your car to look really good with a small budget.
BTW i'm gonna do this for my wifes Kelisa soon.
Might cost more here in Malaysia, so pandai pandai la with budget.

Mighty Car Mods - Season 1 Ep1

if u wanna bolt on, try to find the L70 carb turbo kit.
other than that, no point converting to EFI, and turbo etc... a swap will be better