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.
Ohlins R&T with custom Swift rears, diff lock plate, monroe upper shock mounts