I'm of Polish heritage, hence I have to post this under a fake name.
I've got several recipes for Polish Sausage. They are all basically variations on "pork and beef with lots of garlic". They are good, but they don't have the same magic as the Hilshire Farms, American-supermarket "Polska Keilbasa" product.
The closest I've found is this recipe: http://thespicysausage.com/recipes/polishsausage.htm
It's got a nice sweetness to it, but it's missing... something.
Is there a spice that the americanized version uses that's lacking in this recipe?
Come to think of it... two things I have not tried adding are liquid smoke and Pink Salt. Might those be it?