Welcome @TBonek."Weight savings" is one of the best mods. Every pound you can get rid of ... mats, trunk liner, under the hood - drain 90% of the washer fluid, replace the battery with a lightweight one. Anyone else have some additions without ripping out speakers and such?
Would you get lighter seats, carbon fiber hood and rear hatch and other weight reduction modifications like it?
They can be expensive, but can also make a big difference.