On a budget, the 4x50w into the small speakers would be ok if yo pulled back on the bass, volume,fader and used the sub for the bottom end balance. This would sound reasonably good.
Next up, I'd replace the 4inch speakers with 6inch coaxials so then you could wind up the wick.
I'd run the system with the orig speakers until yo either get fed up with the low volume or alternatively blow them out, then upgrade to 6inch.