I have some Megan coilovers on my car, and i've pretty much drop it to where I like it and set the dampening to stiff. But it feels like it's still too soft, because when I go over bumps and dips it will hit it really hard, so my question is if I tighten the preload on the coilover will it help eliminate some of that?

 

This sounds more like it is too stiff, not soft...
It can also be attributed to high un-sprung weight. You might weigh your tire/rim combination and look at cutting weight there...
Hope others have better advice...
Vince

 

I should have made it clearer, it's not hitting hard because it's stiff... it's hitting what seems like the frame or something hard.