If the Court were to grant Plaintiffs leave to reopen discovery to name a trajectory expert, Defendants would likewise need the opportunity to name an expert and/or a rebuttal expert and would incur additional costs in doing so. See Yeoman v. Ikea U.S. West, Inc., 2013 WL 5727547 at *4 (S.D. Cal. Oct. 22, 2013) (finding additional costs weighed against reopening discovery where a defendant “incur additional costs by having to designate an expert of its own to rebut whatever Plaintiffs new expert offers opinions about, as well as to incur costs reviewing Plaintiffs' expert's opinions and taking the expert's deposition”).