That's my point, the 40/50% I get over get no body work scraping (bumper/Skirts) The other percentage is mainly speed humps which are to high and thing, i.e. can't get my rear wheels on before the front's leave. I don't attempt those.
But I'm retardedly low. So I can promise you you'd be fine with Springs. It's all about how you take a speed bump, I bet there is a speed bump I could get over without scraping, where even a standard ride heighted zed would scrape due to the wrong approach.