It would cost a lot of money to get to 100bhp, so I probably wouldn't bother.
I am not against modifying whatever you have though. If you like the car and can afford it, do what makes you happy. There are a few small-engined cars (including Clios) floating around the club motorsport scene, doing targas, autotests, autosolos and road rallies. You can still have a lot of fun in cars like that and, as
@McGherkin says, it will teach you a LOT about how to drive a car. There is a lovely 1.2 Clio in my local club, with a half cage, buckets etc. It didn't cost them a lot and they have a riot in it. If you do modify it, I would focus on suspension, tyres, brakes and weight reduction and just make sure that anything you fit is cheap-ish, or can be removed and sold on. If you buy the right bits, you could always swap them onto a 172/182 later.
If modifying the car makes you happy, go for it. Life is too short to constantly worry about whether it's worth it or not.