Less base from aftermarket speakers than factory speakers?

I have a 2007 honda civic EX. It has the factory head unit (350 watts) and 7 speakers; 2 in front, 2 in middle, and 3 in the back (1 is a subwoofer right under my rear windshield), and they are all factory speakers. I replaced the front two factory speakers with infinity kappa 52.9i speakers, hoping to get better sound in low and high frequencies. Once I installed them, the high frequencies were much better but more than half of my cars base was gone, because the factory speakers that were in there produced most of the cars base (and it was a lot of base, more than the subwoofer in the back) so I put the factory speakers back in. So basically, I am still looking for replacement speakers to get better high frequences like the infiniti's did, but ALSO to keep that base or make it even better. Which speakers should I go with? Also, I think I might have lost base because the infiniti's were only 5 1/4" while the factory speakers were 6 1/2" and they didn't have a tweeter sticking out like the infinitis did, instead, it is just one flat surface, just like a subwoofer, although it did produce high frequencies such as vocals and acoustics.