The 49ers have been the kings of the NFC West for two consecutive seasons, but staying on top in 2013 is going to be a challenge.Veteran running back Frank Gore has seen the growth and improvement of the Seattle Seahawks – who went to the playoffs last season – and the offseason acquisitions made by the St. Louis Rams and Arizona Cardinals, and knows the Niners have their work cut out for them.As the 49ers veterans arrived for training camp Wednesday in preparation for the team's first full-squad practice Thursday, Gore and his teammates know that they simply can't be as good as they were in 2012. They need to be better."It's probably one of the best divisions in football right now," he told Taylor Price of the team's website. "We like it like that. We like it tough."Though the team obviously wants to get back to the Super Bowl, where it fell just short in February, the No. 1 focus has to be on winning the NFC West."Our main goal is to get better this training camp, be better than last year," he told Price Wednesday, after arriving at the team's training facility in Santa Clara. "Win the first game, win the division and all is right. You win the division and everything...