Stihl MS170 Air Filter/Intake Mod question. This filter has the hole in the center which appears to me to run straight into the carb. Seems like a strange design and gives the opportunity for debris to enter the chainsaw. My MS290 and husky isn't designed that way. Has anyone mated up another filter that would provide better protection? I had a spare MS250 filter that mates up but is to tall for the air filter cover to close on. Thanks