An amp will almost always give you better sound than your HU. Especially for components, which generally require a bit more power to really sound good. Alot of people just get a nice comp set powered by an amp for the fronts, and some coaxials for the rear, just ran off the head unit.
I'm running DLS ur6, cadence 100x2 for them, then a cadence 750x1 to a 10" JL 10w3 in a sealed fiberglass box in the rear all ran off a pioneer premier 860. Sounds good in my Teg.
Front speakers are cake. You even have factory tweeter holes. Rear speakers, I don't know. Never used them.
DLS MS6 MA Audio 100X2 for them, then a MA Audio 400x1 to a Shiva ( returning back to Adire) in a 3ft^3 ported box in the rear running off a Pioneer 9300.