Hi Yorkie,
I've got the factory BOSE system back in right now ready for a sale and the difference was surprising considering it's powering the same set of speakers. Most of my music was streamed through bluetooth and quality was never an issue. Even though everyones tastes are different I could confidently say the Pioneer has a much better sound than the factory bose unit.
Headunit has an equalizer and subwoofer options too so you can change the settings to taste.