Bought a 2012 LSV last fall. The stereo - package A, 4 cabin speakers only, like all stock system is weak.

I am not looking for tower speakers, but am looking to have a descent stereo for cruising or at least hear it while the engine is running.

What is the next basic, best bang for the buck, to improve the stereo?

Adding an Amp between existing head unit and speakers?
Small Sub?

Should I add bow speakers and how much of a PITA is that?

Not looking for a killer system just something that sounds better than whats there.