The stock speakers are not marine rated. You can use almost use anything you want. BestBuy sell Polk's for the same price range as wally world's stuff. Pay attention more to true RMS. Not peak wattage. A speaker rated at 50 to 75 RMS will sound better and an amp will power them nicely. They are more efficient than a speaker that is rated at 300 watts. If you are going to go the amp and 6.5 speaker route then check out HMD or V-twin Audio' site.
2011 Cross Country. D&D's wrapped - VM1DR cams - PC5 - LLoyds high performance filter and ATS (Adjustable Timing system). Power output 115HP/115FTLBS tuned by KMC. Klock Werks flip shield - RF/PBR300x4 amp - Hertz HCX 6.5's - Victory 6X9 Magnum Lids - Victory XM - HMD Black Pull Backs with Victory performance grips. PIAA Led3 driving lights. accessories from Arlen ness - Witch Doctors - Noemtz Designs - Kuryakyn. Blacked out treatment powder Coat by PPC Stuart fl.