A high performance printing system includes a paper tray for holding the blank paper prior to printing. The printer engine demands that the paper size be selected from a limited set of allowable paper sizes. A paper guide mechanism installed in the paper tray has a configuration that operates to guide a paper size having a reduced width relative to a particular allowed paper size. The paper guide mechanism allows reduced width paper to be used in the paper tray, essentially without otherwise adjusting the printing system, such that the printer engine sees the paper size as a particular allowed paper size when a reduced width paper is being used for printing.