It is technically practical to get more out of the boxer NA 1.6L, 1.8L etc motors:
Fit a turbo kit. I ‘ve no experience but at a guess it would be a sudden rush, very peaky and say about another 20% power. Like the turbo cars of 15 – 20 years ago.
Fit a supercharger- I looked at this a few years ago but did not go ahead. I saw dyno prints of examples, they give good low down torque but the top end not a lot more, something like the turbo diesels you can get now. VG for pulling trailers and 0-60 kmph times.
Replace whole motor with a used wrx. Remember to do the chip, exhaust, intake etc.
Replace whole motor with a 2L or even a 2.5L which may be available from wreckers. This would be the simplest and most practical approach, if you get a bigger motor at a good price.
After that you will have performance not up to wrx but well in excess of your car’s suspension and brakes. This may be fun.…

Unless you are like ‘tuna’ on this forum, who clearly knows what he is doing and does most of it himself, I’d say the downside is that the performance:cost is poor value compared with changing the whole car.