Yes, high capacity magazines are legal in PA. The way I understand it is that New York state is still under the 1994 style AWB so possession of a high cap mag made after 1994 is illlegal. So buying post ban hi caps in PA and transporting them into New York would be illegal. As I am not a lawyer you may want to so a little research on this. Try
www.packing.org or
http://www.nraila.org/gunlaws/