-dont go for vs.. not really a big improvement. just to stabilize the voltage. it helps to reduce light from dimming and rpm drop when aircond kicks in..
for me, no fc improvement is seen at all. if u want to get, dont get those imitation pivot/ or malaysian zaptor.. price u pay is not worth for the parts u get.

-first to go for is change the engine air filter. either open pod (k&n,apexi, etc.. HKS mushroom air filter not recommended coz alot imitation) or aftermarket filter drop in filter (redline, works enginerring, etc). (open pod voids warranty though.. and not recommended for auto cars. drop in better for auto and doesnt void warranty)
engine breathing better = better performance

-after that its best to do a cold air intake (CAI) to further improve performance by providing more cold air into the engine.

-stabilizer bars front and rear strut bars for better cornering/ reduce body roll.. down side is that it adds weight to the car.. ultra racing/ctech seems good, lifetime warranty and reasonable price. beware of imitation though.

-another good engine performance upgrade is iridium spark plugs.. typically last 100,000 km or so. provides better combustion = better performance.
typically a set of 4 sticks cost around rm150 plus minus or so for denso iridium. (our viva only needs 3 spark plugs) there are some who sells them separately at approximately rm45 per stick.. if iridium is too expensive for u, u can always opt for sidegapped spark plugs. u can get them from catacombs in lowyat.

-nxt step is extractor and exhaust system.. hotbits for viva full set would set u back rm800 plus minus with installation.. u can opt for custom mix and match with brands such as zenden,hayden,redline etc.. in the right hands it could even perform better without spending much. (voids warranty too)

-nxt u could do is to improve on stability and handling by changing to sport springs / absorber / adjustable (IMPROVE, hotbits, GAB, etc..)
u could opt for better handling performance too by upgrading to ultra light sport rims with wider tyres for better cornering. it is advisable to stick to stock rims size (14 inch etc to maintain FC consumption).
or if u want to go for looks, u could always do 15" 6.5jj or even to crazy to the max and try 15" 7JJ.. or killer gangster fitment 16" 7JJ, flushed to the max. (not recommended on malaysian road and daily drive though haha.. and also FC killers lol)

thats all i could think of for entry level mods.. there are actually more mods to do but it involves more $$$ (exp : piggyback, standalone, etc)

so far the mods ive done is installing stabilizing bars (hotbits) front and back, custom voltage stabilizer, fullset hotbits k&n open pod with heatshield (changed to works engineering drop in filter due to not wanting to void warranty) and CAI. nxt step is to get performance spark plugs and perhaps changing springs/rims.. depends on budget haha.

do share your mods here if u had done any

cheers