My Specialized Rockhopper basic has a KMC narrow chain marked with a "Z". The rear derailleur is a Shimano, as is the front. Neither is marked SIS. I think they are the Acera line. The shifting is quite sloppy. Even on the middle of the 7 cogs it is quite hard to do a front shift. According to my chain gauge I will need to replace the chain soon. Would a Sram chain be appropriate (I like the idea of the power link)? Will a new chain help the adjustment on the shifting?