when you replaced your springs to lower... did you replace your shocks as well...

also what is the setup your running right now... i have a feeling you have a lower quality spring... this shouldn't be happening with rims as small as 16"...

there is one more idea... if you slow the fuck down over speed bumps and pot holes you might not have the same issue.... i suggest you get back to us on those struts... and i have a feeling ur ebay springs just aren't cutting it....