If a guy is faster he will find a way aound you. You should never stop as this will usually only cause more crashes. I would go alittle wide at some point to let them by but other than that hold your line. We are all out there racing for position and if you are always tying to get out of someone's way you are never going to finish well. It's ok to give someone room but hold your line and you will be fine. A fast, consistent racer will know how to manuver around traffic without getting bent out of shape.