I would say you need to take off the splash guards, but you might not be able to get them back on unless you buy new push-in type fasteners. If you don't take them off, the nuts will probably fall out of place. Are you planning on putting them back on? When I took my flares off, I took out the splash guards and left them off. I personally think it looks better, I just need to spray some undercoating under there to protect the paint from rocks.