I for one spent a lot modding my 3-speed auto Wira to get close to 96bhp on wheel. Plenty of grunt and torque on the low to mid but high loses out. But who cares la, I don't need top speed. My car is a Wira, going fast isn't really useful since everything else on the road can go faster than me full out.
The things you mod you'll have to take into consideration how much the gearbox can take. I'm not sure how strong the swift auto GB is, but the 3-speed auto Wira GB is pretty strong to take the beatings I give it without ever breaking.
PNP, lightening and balancing internals, oversized pistons, adjustable cam pulleys + mild cams, AFPR, lightweight wheels, proper exhaust, anything to reduce the strain on the GB will result in more power. 30% power loss is purely at the transmission so if you can lighten the load or increase the overall power to begin with, then you're gonna have a more responsive car.
I really recommend the first thing you do is go source for an ultra lightweight rim and good tyres. My 15" + 205/50/15 tyres weigh less than a stock myvi rim + tyre (14" rims). That made a huge difference in performance already.
Then only start going for high compression setup like high compression pistons, or the cheating method of using thinner gaskets or just skim the head.
Once you get used to that power then only start doing more like oversized pistons, and all other internal mods. Never go to the turbo with an auto. That's way more fun manual.