well X2.5035 is the newest bios that you can use on your modchip but i use X2.5032 myself... it's 512KB in size and thats generally the size of bios that you need to use anyways... use "FlashX v1.2" (im assuming your xbox is already in good running order) to update the bios to this new x2.5032 (or x2.5035) version.
