base: dual runner plastic intake manifold, lower compression pistons, different cams, different ecu/vtec timing, valve springs, smaller wheels, smaller rear rotors and calipers, slightly more restricive exhaust, other stuff cant think of.

s: single runner high volume aluminun intake manifold, slightly larger tb? i think, 11:1 compression pistons, stronger valve springs,

all in all there is a 40 hp difference. with everything you can do to the base you can do at least that with the types. in the long run however i think the base will better for boost since its built around a lower compression ratio, but i dont know what your money plans are.