How to increase power without decreasing fun

New owner of a 1.8 2003 nb. What are some mods that wil make the miata a bit faster, without ruining the handling and character of the car. Ive heard that turbos kinda ruin the reliability and "miata-ness" and i cant straightpipe it or swap out the engine because i live in belgium and the regulations are strict. I also cant change the emissions too much Maybe a slightly better exhaust/muffler or a slight tune? I also need the car to keep its reliability and i would prefer it if the mods wouldnt be way too expensive.