mod air filter, might be a good start, it is better u buy K&N, dun buy those cap ayam 1, it is useless and damage ur engine. u can buy drop in or open pod, if u lazy wanna modify ur intake piping, go for drop in, drop in not bad either.
your exhaust system, stay original also can, if u plan to modify, piping dont too big, and muffler dont too big, u will loss power. for extractor go for powerzone brand, dun buy cap ayam, useless too. btw extractor powerzone for NA only, not for turbo.
for turbo, is a really big thing, u will get a big increment power, but there is lot of work for a modern engine to bolt on turbo.
you have to buy turbo exhaust manifold, not sure bout avy's manifold can fit it or not, you nid turbo, piping, intercooler. u might nid to modify your fuel regulator to adjustable, the fuel rail have to modify, if not mistaken viva same with kelisa or myvi, it doesnt have fuel return line, even injector and fuel pump you nid to modify to bigger flow.
another 1, you nid piggyback system such as e-manage or afc to control your air fuel ratio, standard ecu not suitable for an engine that bolted on turbo.
the cost quite expensive, and you only can run low boost, due to NA engine compression is high. it is better if u buy the whole engine, maybe YRV? 1.3 turbo.