why will it be extremely poor?
why are you saying that? depends what you buy. i have the stock one's in at the mo and they sound ok.
and it also depends on what headunit you have.
get a decent headunit, alpine one or similar, and get a 13cm component set, mount the tweeter on the a piller, and if you want a small 2 channel amp, and it should sound good.
alpine type e should be goodenough for most people