What stock system do u have? If you have the "base" system with 6 speakers and no tweeters it gives you a huge improvement to staging, SPL, clarity and tonality, even more so if you add a centre speaker. Bass performance is also increased but not dramatically. I'd assume it would offer the same benefits to the hifi system as well.
Turbo Dynamics Hybrid Turbos, Wagner Intercooler, DPF Delete Pipe with Sports Cat, Ecotune custom map ~ 422bhp & 618ft.lbs
Ohlins R&T with custom Swift rears