You've probably all been here before but whats the best battery to fit an FE400E,something with a bit of grunt and without having to modify the battery box.Rumor has it a Yuasa YTZ7S will do the job?.I just need to know if thats the case, will it fit without any mods and, will the cover still fit on.I've got a 5amp at present and thats naff.......anyone ???