I've run around 20 runs on my car since and i haven't seen a problem with debris build up yet. But it wouldn't be that hard to pull the cover off the bottom and blow it out with an aircompressor. I really don't know how much i took off. I did it inside a garbage can to save myself from cleaning up a mess and there was a bunch of junk in it in the end. My best guess would be around 1/5, that is how much i took off.